1692 lines
50 KiB
Haskell
1692 lines
50 KiB
Haskell
{-# LANGUAGE DefaultSignatures #-}
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{-# LANGUAGE DeriveFunctor #-}
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{-# LANGUAGE DeriveGeneric #-}
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{-# LANGUAGE FlexibleInstances #-}
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{-# LANGUAGE FlexibleContexts #-}
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{-# LANGUAGE GeneralizedNewtypeDeriving #-}
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{-# LANGUAGE OverloadedStrings #-}
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{-# LANGUAGE RankNTypes #-}
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{-# LANGUAGE RecordWildCards #-}
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{-# LANGUAGE ScopedTypeVariables #-}
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{-# LANGUAGE StandaloneDeriving #-}
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{-# LANGUAGE TypeOperators #-}
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{-# LANGUAGE TupleSections #-}
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{-| Please read the "Dhall.Tutorial" module, which contains a tutorial explaining
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how to use the language, the compiler, and this library
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-}
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module Dhall
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(
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-- * Input
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input
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, inputWithSettings
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, inputFile
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, inputFileWithSettings
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, inputExpr
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, inputExprWithSettings
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, rootDirectory
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, sourceName
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, startingContext
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, normalizer
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, standardVersion
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, defaultInputSettings
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, InputSettings
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, defaultEvaluateSettings
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, EvaluateSettings
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, HasEvaluateSettings
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, detailed
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-- * Types
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, Type(..)
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, RecordType(..)
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, UnionType(..)
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, InputType(..)
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, Interpret(..)
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, InvalidType(..)
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, auto
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, genericAuto
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, InterpretOptions(..)
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, defaultInterpretOptions
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, bool
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, natural
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, integer
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, scientific
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, double
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, lazyText
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, strictText
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, maybe
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, sequence
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, list
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, vector
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, unit
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, string
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, pair
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, record
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, field
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, union
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, constructor
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, GenericInterpret(..)
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, GenericInject(..)
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, Inject(..)
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, inject
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, RecordInputType(..)
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, inputFieldWith
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, inputField
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, inputRecord
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, UnionInputType(..)
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, inputConstructorWith
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, inputConstructor
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, inputUnion
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, (>|<)
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-- * Miscellaneous
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, rawInput
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, (>$<)
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, (>*<)
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-- * Re-exports
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, Natural
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, Seq
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, Text
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, Vector
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, Generic
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) where
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import Control.Applicative (empty, liftA2, (<|>), Alternative)
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import Control.Exception (Exception)
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import Control.Monad.Trans.State.Strict
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import Control.Monad (guard)
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import Data.Coerce (coerce)
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import Data.Functor.Contravariant (Contravariant(..), (>$<), Op(..))
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import Data.Functor.Contravariant.Divisible (Divisible(..), divided)
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import Data.Monoid ((<>))
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import Data.Scientific (Scientific)
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import Data.Sequence (Seq)
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import Data.Text (Text)
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import Data.Typeable (Typeable)
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import Data.Vector (Vector)
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import Data.Word (Word8, Word16, Word32, Word64)
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import Dhall.Binary (StandardVersion(..))
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import Dhall.Core (Expr(..), Chunks(..))
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import Dhall.Import (Imported(..))
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import Dhall.Parser (Src(..))
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import Dhall.TypeCheck (DetailedTypeError(..), TypeError, X)
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import GHC.Generics
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import Lens.Family (LensLike', set, view)
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import Numeric.Natural (Natural)
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import Prelude hiding (maybe, sequence)
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import System.FilePath (takeDirectory)
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import qualified Control.Applicative
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import qualified Control.Exception
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import qualified Control.Monad.Trans.State.Strict as State
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import qualified Data.Foldable
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import qualified Data.Functor.Compose
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import qualified Data.Functor.Product
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import qualified Data.Semigroup
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import qualified Data.Scientific
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import qualified Data.Sequence
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import qualified Data.Set
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import qualified Data.Text
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import qualified Data.Text.IO
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import qualified Data.Text.Lazy
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import qualified Data.Vector
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import qualified Dhall.Binary
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import qualified Dhall.Context
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import qualified Dhall.Core
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import qualified Dhall.Import
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import qualified Dhall.Map
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import qualified Dhall.Parser
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import qualified Dhall.Pretty.Internal
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import qualified Dhall.TypeCheck
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-- $setup
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-- >>> :set -XOverloadedStrings
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throws :: Exception e => Either e a -> IO a
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throws (Left e) = Control.Exception.throwIO e
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throws (Right r) = return r
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{-| Every `Type` must obey the contract that if an expression's type matches the
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the `expected` type then the `extract` function must succeed. If not, then
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this exception is thrown
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This exception indicates that an invalid `Type` was provided to the `input`
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function
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-}
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data InvalidType = InvalidType deriving (Typeable)
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_ERROR :: String
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_ERROR = "\ESC[1;31mError\ESC[0m"
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instance Show InvalidType where
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show InvalidType =
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_ERROR <> ": Invalid Dhall.Type \n\
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\ \n\
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\Every Type must provide an extract function that succeeds if an expression \n\
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\matches the expected type. You provided a Type that disobeys this contract \n"
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instance Exception InvalidType
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-- | @since 1.16
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data InputSettings = InputSettings
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{ _rootDirectory :: FilePath
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, _sourceName :: FilePath
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, _evaluateSettings :: EvaluateSettings
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}
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-- | Default input settings: resolves imports relative to @.@ (the
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-- current working directory), report errors as coming from @(input)@,
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-- and default evaluation settings from 'defaultEvaluateSettings'.
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--
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-- @since 1.16
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defaultInputSettings :: InputSettings
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defaultInputSettings = InputSettings
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{ _rootDirectory = "."
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, _sourceName = "(input)"
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, _evaluateSettings = defaultEvaluateSettings
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}
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-- | Access the directory to resolve imports relative to.
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--
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-- @since 1.16
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rootDirectory
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:: (Functor f)
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=> LensLike' f InputSettings FilePath
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rootDirectory k s =
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fmap (\x -> s { _rootDirectory = x }) (k (_rootDirectory s))
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-- | Access the name of the source to report locations from; this is
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-- only used in error messages, so it's okay if this is a best guess
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-- or something symbolic.
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--
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-- @since 1.16
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sourceName
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:: (Functor f)
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=> LensLike' f InputSettings FilePath
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sourceName k s =
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fmap (\x -> s { _sourceName = x}) (k (_sourceName s))
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-- | @since 1.16
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data EvaluateSettings = EvaluateSettings
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{ _startingContext :: Dhall.Context.Context (Expr Src X)
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, _normalizer :: Dhall.Core.ReifiedNormalizer X
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, _standardVersion :: StandardVersion
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}
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-- | Default evaluation settings: no extra entries in the initial
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-- context, and no special normalizer behaviour.
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--
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-- @since 1.16
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defaultEvaluateSettings :: EvaluateSettings
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defaultEvaluateSettings = EvaluateSettings
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{ _startingContext = Dhall.Context.empty
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, _normalizer = Dhall.Core.ReifiedNormalizer (const (pure Nothing))
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, _standardVersion = Dhall.Binary.defaultStandardVersion
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}
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-- | Access the starting context used for evaluation and type-checking.
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--
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-- @since 1.16
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startingContext
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:: (Functor f, HasEvaluateSettings s)
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=> LensLike' f s (Dhall.Context.Context (Expr Src X))
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startingContext = evaluateSettings . l
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where
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l :: (Functor f)
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=> LensLike' f EvaluateSettings (Dhall.Context.Context (Expr Src X))
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l k s = fmap (\x -> s { _startingContext = x}) (k (_startingContext s))
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-- | Access the custom normalizer.
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--
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-- @since 1.16
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normalizer
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:: (Functor f, HasEvaluateSettings s)
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=> LensLike' f s (Dhall.Core.ReifiedNormalizer X)
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normalizer = evaluateSettings . l
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where
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l :: (Functor f)
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=> LensLike' f EvaluateSettings (Dhall.Core.ReifiedNormalizer X)
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l k s = fmap (\x -> s { _normalizer = x }) (k (_normalizer s))
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-- | Access the standard version (used primarily when encoding or decoding
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-- Dhall expressions to and from a binary representation)
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--
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-- @since 1.17
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standardVersion
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:: (Functor f, HasEvaluateSettings s)
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=> LensLike' f s StandardVersion
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standardVersion = evaluateSettings . l
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where
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l k s = fmap (\x -> s { _standardVersion = x}) (k (_standardVersion s))
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-- | @since 1.16
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class HasEvaluateSettings s where
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evaluateSettings
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:: (Functor f)
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=> LensLike' f s EvaluateSettings
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instance HasEvaluateSettings InputSettings where
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evaluateSettings k s =
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fmap (\x -> s { _evaluateSettings = x }) (k (_evaluateSettings s))
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instance HasEvaluateSettings EvaluateSettings where
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evaluateSettings = id
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{-| Type-check and evaluate a Dhall program, decoding the result into Haskell
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The first argument determines the type of value that you decode:
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>>> input integer "+2"
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2
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>>> input (vector double) "[1.0, 2.0]"
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[1.0,2.0]
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Use `auto` to automatically select which type to decode based on the
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inferred return type:
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>>> input auto "True" :: IO Bool
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True
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This uses the settings from 'defaultInputSettings'.
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-}
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input
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:: Type a
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-- ^ The type of value to decode from Dhall to Haskell
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-> Text
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-- ^ The Dhall program
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-> IO a
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-- ^ The decoded value in Haskell
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input =
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inputWithSettings defaultInputSettings
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{-| Extend 'input' with a root directory to resolve imports relative
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to, a file to mention in errors as the source, a custom typing
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context, and a custom normalization process.
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@since 1.16
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-}
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inputWithSettings
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:: InputSettings
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-> Type a
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-- ^ The type of value to decode from Dhall to Haskell
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-> Text
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-- ^ The Dhall program
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-> IO a
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-- ^ The decoded value in Haskell
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inputWithSettings settings (Type {..}) txt = do
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expr <- throws (Dhall.Parser.exprFromText (view sourceName settings) txt)
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let InputSettings {..} = settings
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let EvaluateSettings {..} = _evaluateSettings
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let transform =
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set Dhall.Import.standardVersion _standardVersion
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. set Dhall.Import.normalizer _normalizer
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. set Dhall.Import.startingContext _startingContext
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let status = transform (Dhall.Import.emptyStatus _rootDirectory)
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expr' <- State.evalStateT (Dhall.Import.loadWith expr) status
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let suffix = Dhall.Pretty.Internal.prettyToStrictText expected
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let annot = case expr' of
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Note (Src begin end bytes) _ ->
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Note (Src begin end bytes') (Annot expr' expected)
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where
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bytes' = bytes <> " : " <> suffix
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_ ->
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Annot expr' expected
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_ <- throws (Dhall.TypeCheck.typeWith (view startingContext settings) annot)
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case extract (Dhall.Core.normalizeWith (Dhall.Core.getReifiedNormalizer (view normalizer settings)) expr') of
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Just x -> return x
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Nothing -> Control.Exception.throwIO InvalidType
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{-| Type-check and evaluate a Dhall program that is read from the
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file-system.
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This uses the settings from 'defaultEvaluateSettings'.
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@since 1.16
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-}
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inputFile
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:: Type a
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-- ^ The type of value to decode from Dhall to Haskell
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-> FilePath
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-- ^ The path to the Dhall program.
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-> IO a
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-- ^ The decoded value in Haskell.
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inputFile =
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inputFileWithSettings defaultEvaluateSettings
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{-| Extend 'inputFile' with a custom typing context and a custom
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normalization process.
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@since 1.16
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-}
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inputFileWithSettings
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:: EvaluateSettings
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-> Type a
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-- ^ The type of value to decode from Dhall to Haskell
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-> FilePath
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-- ^ The path to the Dhall program.
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-> IO a
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-- ^ The decoded value in Haskell.
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inputFileWithSettings settings ty path = do
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text <- Data.Text.IO.readFile path
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let inputSettings = InputSettings
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{ _rootDirectory = takeDirectory path
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, _sourceName = path
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, _evaluateSettings = settings
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}
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inputWithSettings inputSettings ty text
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{-| Similar to `input`, but without interpreting the Dhall `Expr` into a Haskell
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type.
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Uses the settings from 'defaultInputSettings'.
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-}
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inputExpr
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:: Text
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-- ^ The Dhall program
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-> IO (Expr Src X)
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-- ^ The fully normalized AST
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inputExpr =
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inputExprWithSettings defaultInputSettings
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{-| Extend 'inputExpr' with a root directory to resolve imports relative
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to, a file to mention in errors as the source, a custom typing
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context, and a custom normalization process.
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@since 1.16
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-}
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inputExprWithSettings
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:: InputSettings
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-> Text
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-- ^ The Dhall program
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-> IO (Expr Src X)
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-- ^ The fully normalized AST
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inputExprWithSettings settings txt = do
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expr <- throws (Dhall.Parser.exprFromText (view sourceName settings) txt)
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let InputSettings {..} = settings
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let EvaluateSettings {..} = _evaluateSettings
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let transform =
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set Dhall.Import.standardVersion _standardVersion
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. set Dhall.Import.normalizer _normalizer
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. set Dhall.Import.startingContext _startingContext
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let status = transform (Dhall.Import.emptyStatus _rootDirectory)
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expr' <- State.evalStateT (Dhall.Import.loadWith expr) status
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_ <- throws (Dhall.TypeCheck.typeWith (view startingContext settings) expr')
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pure (Dhall.Core.normalizeWith (Dhall.Core.getReifiedNormalizer (view normalizer settings)) expr')
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-- | Use this function to extract Haskell values directly from Dhall AST.
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-- The intended use case is to allow easy extraction of Dhall values for
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-- making the function `Dhall.Core.normalizeWith` easier to use.
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--
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-- For other use cases, use `input` from `Dhall` module. It will give you
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-- a much better user experience.
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rawInput
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:: Alternative f
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=> Type a
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-- ^ The type of value to decode from Dhall to Haskell
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-> Expr s X
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-- ^ a closed form Dhall program, which evaluates to the expected type
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-> f a
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-- ^ The decoded value in Haskell
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rawInput (Type {..}) expr = do
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case extract (Dhall.Core.normalize expr) of
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Just x -> pure x
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Nothing -> empty
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{-| Use this to provide more detailed error messages
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>> input auto "True" :: IO Integer
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> *** Exception: Error: Expression doesn't match annotation
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>
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> True : Integer
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>
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> (input):1:1
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>> detailed (input auto "True") :: IO Integer
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> *** Exception: Error: Expression doesn't match annotation
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>
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> Explanation: You can annotate an expression with its type or kind using the
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> ❰:❱ symbol, like this:
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>
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>
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> ┌───────┐
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> │ x : t │ ❰x❱ is an expression and ❰t❱ is the annotated type or kind of ❰x❱
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> └───────┘
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>
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> The type checker verifies that the expression's type or kind matches the
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> provided annotation
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>
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> For example, all of the following are valid annotations that the type checker
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> accepts:
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>
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>
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> ┌─────────────┐
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> │ 1 : Natural │ ❰1❱ is an expression that has type ❰Natural❱, so the type
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> └─────────────┘ checker accepts the annotation
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>
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>
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> ┌───────────────────────┐
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> │ Natural/even 2 : Bool │ ❰Natural/even 2❱ has type ❰Bool❱, so the type
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> └───────────────────────┘ checker accepts the annotation
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>
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>
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> ┌────────────────────┐
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> │ List : Type → Type │ ❰List❱ is an expression that has kind ❰Type → Type❱,
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> └────────────────────┘ so the type checker accepts the annotation
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>
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>
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> ┌──────────────────┐
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> │ List Text : Type │ ❰List Text❱ is an expression that has kind ❰Type❱, so
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> └──────────────────┘ the type checker accepts the annotation
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>
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>
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> However, the following annotations are not valid and the type checker will
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> reject them:
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>
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>
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> ┌──────────┐
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> │ 1 : Text │ The type checker rejects this because ❰1❱ does not have type
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> └──────────┘ ❰Text❱
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>
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>
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> ┌─────────────┐
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> │ List : Type │ ❰List❱ does not have kind ❰Type❱
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> └─────────────┘
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>
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>
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> You or the interpreter annotated this expression:
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>
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> ↳ True
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>
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> ... with this type or kind:
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>
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> ↳ Integer
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>
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> ... but the inferred type or kind of the expression is actually:
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>
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> ↳ Bool
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>
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> Some common reasons why you might get this error:
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>
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> ● The Haskell Dhall interpreter implicitly inserts a top-level annotation
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> matching the expected type
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>
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> For example, if you run the following Haskell code:
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>
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>
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> ┌───────────────────────────────┐
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> │ >>> input auto "1" :: IO Text │
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> └───────────────────────────────┘
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>
|
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>
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> ... then the interpreter will actually type check the following annotated
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> expression:
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>
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>
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> ┌──────────┐
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> │ 1 : Text │
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> └──────────┘
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>
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>
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> ... and then type-checking will fail
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>
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> ────────────────────────────────────────────────────────────────────────────────
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>
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> True : Integer
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>
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> (input):1:1
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-}
|
|
detailed :: IO a -> IO a
|
|
detailed =
|
|
Control.Exception.handle handler1 . Control.Exception.handle handler0
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|
where
|
|
handler0 :: Imported (TypeError Src X) -> IO a
|
|
handler0 (Imported ps e) =
|
|
Control.Exception.throwIO (Imported ps (DetailedTypeError e))
|
|
|
|
handler1 :: TypeError Src X -> IO a
|
|
handler1 e = Control.Exception.throwIO (DetailedTypeError e)
|
|
|
|
{-| A @(Type a)@ represents a way to marshal a value of type @\'a\'@ from Dhall
|
|
into Haskell
|
|
|
|
You can produce `Type`s either explicitly:
|
|
|
|
> example :: Type (Vector Text)
|
|
> example = vector text
|
|
|
|
... or implicitly using `auto`:
|
|
|
|
> example :: Type (Vector Text)
|
|
> example = auto
|
|
|
|
You can consume `Type`s using the `input` function:
|
|
|
|
> input :: Type a -> Text -> IO a
|
|
-}
|
|
data Type a = Type
|
|
{ extract :: Expr Src X -> Maybe a
|
|
-- ^ Extracts Haskell value from the Dhall expression
|
|
, expected :: Expr Src X
|
|
-- ^ Dhall type of the Haskell value
|
|
}
|
|
deriving (Functor)
|
|
|
|
{-| Decode a `Bool`
|
|
|
|
>>> input bool "True"
|
|
True
|
|
-}
|
|
bool :: Type Bool
|
|
bool = Type {..}
|
|
where
|
|
extract (BoolLit b) = pure b
|
|
extract _ = Nothing
|
|
|
|
expected = Bool
|
|
|
|
{-| Decode a `Natural`
|
|
|
|
>>> input natural "42"
|
|
42
|
|
-}
|
|
natural :: Type Natural
|
|
natural = Type {..}
|
|
where
|
|
extract (NaturalLit n) = pure n
|
|
extract _ = empty
|
|
|
|
expected = Natural
|
|
|
|
{-| Decode an `Integer`
|
|
|
|
>>> input integer "+42"
|
|
42
|
|
-}
|
|
integer :: Type Integer
|
|
integer = Type {..}
|
|
where
|
|
extract (IntegerLit n) = pure n
|
|
extract _ = empty
|
|
|
|
expected = Integer
|
|
|
|
{-| Decode a `Scientific`
|
|
|
|
>>> input scientific "1e100"
|
|
1.0e100
|
|
-}
|
|
scientific :: Type Scientific
|
|
scientific = fmap Data.Scientific.fromFloatDigits double
|
|
|
|
{-| Decode a `Double`
|
|
|
|
>>> input double "42.0"
|
|
42.0
|
|
-}
|
|
double :: Type Double
|
|
double = Type {..}
|
|
where
|
|
extract (DoubleLit n) = pure n
|
|
extract _ = empty
|
|
|
|
expected = Double
|
|
|
|
{-| Decode lazy `Text`
|
|
|
|
>>> input lazyText "\"Test\""
|
|
"Test"
|
|
-}
|
|
lazyText :: Type Data.Text.Lazy.Text
|
|
lazyText = Type {..}
|
|
where
|
|
extract (TextLit (Chunks [] t)) = pure (Data.Text.Lazy.fromStrict t)
|
|
extract _ = empty
|
|
|
|
expected = Text
|
|
|
|
{-| Decode strict `Text`
|
|
|
|
>>> input strictText "\"Test\""
|
|
"Test"
|
|
-}
|
|
strictText :: Type Text
|
|
strictText = fmap Data.Text.Lazy.toStrict lazyText
|
|
|
|
{-| Decode a `Maybe`
|
|
|
|
>>> input (maybe natural) "Some 1"
|
|
Just 1
|
|
-}
|
|
maybe :: Type a -> Type (Maybe a)
|
|
maybe (Type extractIn expectedIn) = Type extractOut expectedOut
|
|
where
|
|
extractOut (Some e ) = fmap Just (extractIn e)
|
|
extractOut (App None _) = return Nothing
|
|
extractOut _ = empty
|
|
|
|
expectedOut = App Optional expectedIn
|
|
|
|
{-| Decode a `Seq`
|
|
|
|
>>> input (sequence natural) "[1, 2, 3]"
|
|
fromList [1,2,3]
|
|
-}
|
|
sequence :: Type a -> Type (Seq a)
|
|
sequence (Type extractIn expectedIn) = Type extractOut expectedOut
|
|
where
|
|
extractOut (ListLit _ es) = traverse extractIn es
|
|
extractOut _ = Nothing
|
|
|
|
expectedOut = App List expectedIn
|
|
|
|
{-| Decode a list
|
|
|
|
>>> input (list natural) "[1, 2, 3]"
|
|
[1,2,3]
|
|
-}
|
|
list :: Type a -> Type [a]
|
|
list = fmap Data.Foldable.toList . sequence
|
|
|
|
{-| Decode a `Vector`
|
|
|
|
>>> input (vector natural) "[1, 2, 3]"
|
|
[1,2,3]
|
|
-}
|
|
vector :: Type a -> Type (Vector a)
|
|
vector = fmap Data.Vector.fromList . list
|
|
|
|
{-| Decode @()@ from an empty record.
|
|
|
|
>>> input unit "{=}" -- GHC doesn't print the result if it is ()
|
|
|
|
-}
|
|
unit :: Type ()
|
|
unit = Type extractOut expectedOut
|
|
where
|
|
extractOut (RecordLit fields)
|
|
| Data.Foldable.null fields = return ()
|
|
extractOut _ = Nothing
|
|
|
|
expectedOut = Record mempty
|
|
|
|
{-| Decode a `String`
|
|
|
|
>>> input string "\"ABC\""
|
|
"ABC"
|
|
|
|
-}
|
|
string :: Type String
|
|
string = Data.Text.Lazy.unpack <$> lazyText
|
|
|
|
{-| Given a pair of `Type`s, decode a tuple-record into their pairing.
|
|
|
|
>>> input (pair natural bool) "{ _1 = 42, _2 = False }"
|
|
(42,False)
|
|
-}
|
|
pair :: Type a -> Type b -> Type (a, b)
|
|
pair l r = Type extractOut expectedOut
|
|
where
|
|
extractOut (RecordLit fields) =
|
|
(,) <$> ( Dhall.Map.lookup "_1" fields >>= extract l )
|
|
<*> ( Dhall.Map.lookup "_2" fields >>= extract r )
|
|
extractOut _ = Nothing
|
|
|
|
expectedOut =
|
|
Record
|
|
(Dhall.Map.fromList
|
|
[ ("_1", expected l)
|
|
, ("_2", expected r)
|
|
]
|
|
)
|
|
|
|
{-| Any value that implements `Interpret` can be automatically decoded based on
|
|
the inferred return type of `input`
|
|
|
|
>>> input auto "[1, 2, 3]" :: IO (Vector Natural)
|
|
[1,2,3]
|
|
|
|
This class auto-generates a default implementation for records that
|
|
implement `Generic`. This does not auto-generate an instance for recursive
|
|
types.
|
|
-}
|
|
class Interpret a where
|
|
autoWith:: InterpretOptions -> Type a
|
|
default autoWith
|
|
:: (Generic a, GenericInterpret (Rep a)) => InterpretOptions -> Type a
|
|
autoWith options = fmap GHC.Generics.to (evalState (genericAutoWith options) 1)
|
|
|
|
instance Interpret Bool where
|
|
autoWith _ = bool
|
|
|
|
instance Interpret Natural where
|
|
autoWith _ = natural
|
|
|
|
instance Interpret Integer where
|
|
autoWith _ = integer
|
|
|
|
instance Interpret Scientific where
|
|
autoWith _ = scientific
|
|
|
|
instance Interpret Double where
|
|
autoWith _ = double
|
|
|
|
instance {-# OVERLAPS #-} Interpret [Char] where
|
|
autoWith _ = string
|
|
|
|
instance Interpret Data.Text.Lazy.Text where
|
|
autoWith _ = lazyText
|
|
|
|
instance Interpret Text where
|
|
autoWith _ = strictText
|
|
|
|
instance Interpret a => Interpret (Maybe a) where
|
|
autoWith opts = maybe (autoWith opts)
|
|
|
|
instance Interpret a => Interpret (Seq a) where
|
|
autoWith opts = sequence (autoWith opts)
|
|
|
|
instance Interpret a => Interpret [a] where
|
|
autoWith = fmap (fmap Data.Vector.toList) autoWith
|
|
|
|
instance Interpret a => Interpret (Vector a) where
|
|
autoWith opts = vector (autoWith opts)
|
|
|
|
instance (Inject a, Interpret b) => Interpret (a -> b) where
|
|
autoWith opts = Type extractOut expectedOut
|
|
where
|
|
normalizer_ = Dhall.Core.getReifiedNormalizer (inputNormalizer opts)
|
|
|
|
extractOut e = Just (\i -> case extractIn (Dhall.Core.normalizeWith normalizer_ (App e (embed i))) of
|
|
Just o -> o
|
|
Nothing -> error "Interpret: You cannot decode a function if it does not have the correct type" )
|
|
|
|
expectedOut = Pi "_" declared expectedIn
|
|
|
|
InputType {..} = inject
|
|
|
|
Type extractIn expectedIn = autoWith opts
|
|
|
|
instance (Interpret a, Interpret b) => Interpret (a, b)
|
|
|
|
{-| Use the default options for interpreting a configuration file
|
|
|
|
> auto = autoWith defaultInterpretOptions
|
|
-}
|
|
auto :: Interpret a => Type a
|
|
auto = autoWith defaultInterpretOptions
|
|
|
|
{-| `genericAuto` is the default implementation for `auto` if you derive
|
|
`Interpret`. The difference is that you can use `genericAuto` without
|
|
having to explicitly provide an `Interpret` instance for a type as long as
|
|
the type derives `Generic`
|
|
-}
|
|
genericAuto :: (Generic a, GenericInterpret (Rep a)) => Type a
|
|
genericAuto = fmap to (evalState (genericAutoWith defaultInterpretOptions) 1)
|
|
|
|
{-| Use these options to tweak how Dhall derives a generic implementation of
|
|
`Interpret`
|
|
-}
|
|
data InterpretOptions = InterpretOptions
|
|
{ fieldModifier :: Text -> Text
|
|
-- ^ Function used to transform Haskell field names into their corresponding
|
|
-- Dhall field names
|
|
, constructorModifier :: Text -> Text
|
|
-- ^ Function used to transform Haskell constructor names into their
|
|
-- corresponding Dhall alternative names
|
|
, inputNormalizer :: Dhall.Core.ReifiedNormalizer X
|
|
-- ^ This is only used by the `Interpret` instance for functions in order
|
|
-- to normalize the function input before marshaling the input into a
|
|
-- Dhall expression
|
|
}
|
|
|
|
{-| Default interpret options, which you can tweak or override, like this:
|
|
|
|
> autoWith
|
|
> (defaultInterpretOptions { fieldModifier = Data.Text.Lazy.dropWhile (== '_') })
|
|
-}
|
|
defaultInterpretOptions :: InterpretOptions
|
|
defaultInterpretOptions = InterpretOptions
|
|
{ fieldModifier = id
|
|
, constructorModifier = id
|
|
, inputNormalizer = Dhall.Core.ReifiedNormalizer (const (pure Nothing))
|
|
}
|
|
|
|
{-| This is the underlying class that powers the `Interpret` class's support
|
|
for automatically deriving a generic implementation
|
|
-}
|
|
class GenericInterpret f where
|
|
genericAutoWith :: InterpretOptions -> State Int (Type (f a))
|
|
|
|
instance GenericInterpret f => GenericInterpret (M1 D d f) where
|
|
genericAutoWith options = do
|
|
res <- genericAutoWith options
|
|
pure (fmap M1 res)
|
|
|
|
instance GenericInterpret V1 where
|
|
genericAutoWith _ = pure Type {..}
|
|
where
|
|
extract _ = Nothing
|
|
|
|
expected = Union mempty
|
|
|
|
unsafeExpectUnion :: Text -> Expr Src X -> Dhall.Map.Map Text (Expr Src X)
|
|
unsafeExpectUnion _ (Union kts) =
|
|
kts
|
|
unsafeExpectUnion name expression =
|
|
Dhall.Core.internalError
|
|
(name <> ": Unexpected constructor: " <> Dhall.Core.pretty expression)
|
|
|
|
unsafeExpectRecord :: Text -> Expr Src X -> Dhall.Map.Map Text (Expr Src X)
|
|
unsafeExpectRecord _ (Record kts) =
|
|
kts
|
|
unsafeExpectRecord name expression =
|
|
Dhall.Core.internalError
|
|
(name <> ": Unexpected constructor: " <> Dhall.Core.pretty expression)
|
|
|
|
unsafeExpectUnionLit
|
|
:: Text -> Expr Src X -> (Text, Expr Src X, Dhall.Map.Map Text (Expr Src X))
|
|
unsafeExpectUnionLit _ (UnionLit k v kts) =
|
|
(k, v, kts)
|
|
unsafeExpectUnionLit name expression =
|
|
Dhall.Core.internalError
|
|
(name <> ": Unexpected constructor: " <> Dhall.Core.pretty expression)
|
|
|
|
unsafeExpectRecordLit :: Text -> Expr Src X -> Dhall.Map.Map Text (Expr Src X)
|
|
unsafeExpectRecordLit _ (RecordLit kvs) =
|
|
kvs
|
|
unsafeExpectRecordLit name expression =
|
|
Dhall.Core.internalError
|
|
(name <> ": Unexpected constructor: " <> Dhall.Core.pretty expression)
|
|
|
|
instance (Constructor c1, Constructor c2, GenericInterpret f1, GenericInterpret f2) => GenericInterpret (M1 C c1 f1 :+: M1 C c2 f2) where
|
|
genericAutoWith options@(InterpretOptions {..}) = pure (Type {..})
|
|
where
|
|
nL :: M1 i c1 f1 a
|
|
nL = undefined
|
|
|
|
nR :: M1 i c2 f2 a
|
|
nR = undefined
|
|
|
|
nameL = constructorModifier (Data.Text.pack (conName nL))
|
|
nameR = constructorModifier (Data.Text.pack (conName nR))
|
|
|
|
extract (UnionLit name e _)
|
|
| name == nameL = fmap (L1 . M1) (extractL e)
|
|
| name == nameR = fmap (R1 . M1) (extractR e)
|
|
| otherwise = Nothing
|
|
extract _ = Nothing
|
|
|
|
expected =
|
|
Union (Dhall.Map.fromList [(nameL, expectedL), (nameR, expectedR)])
|
|
|
|
Type extractL expectedL = evalState (genericAutoWith options) 1
|
|
Type extractR expectedR = evalState (genericAutoWith options) 1
|
|
|
|
instance (Constructor c, GenericInterpret (f :+: g), GenericInterpret h) => GenericInterpret ((f :+: g) :+: M1 C c h) where
|
|
genericAutoWith options@(InterpretOptions {..}) = pure (Type {..})
|
|
where
|
|
n :: M1 i c h a
|
|
n = undefined
|
|
|
|
name = constructorModifier (Data.Text.pack (conName n))
|
|
|
|
extract u@(UnionLit name' e _)
|
|
| name == name' = fmap (R1 . M1) (extractR e)
|
|
| otherwise = fmap L1 (extractL u)
|
|
extract _ = Nothing
|
|
|
|
expected =
|
|
Union (Dhall.Map.insert name expectedR ktsL)
|
|
|
|
Type extractL expectedL = evalState (genericAutoWith options) 1
|
|
Type extractR expectedR = evalState (genericAutoWith options) 1
|
|
|
|
ktsL = unsafeExpectUnion "genericAutoWith (:+:)" expectedL
|
|
|
|
instance (Constructor c, GenericInterpret f, GenericInterpret (g :+: h)) => GenericInterpret (M1 C c f :+: (g :+: h)) where
|
|
genericAutoWith options@(InterpretOptions {..}) = pure (Type {..})
|
|
where
|
|
n :: M1 i c f a
|
|
n = undefined
|
|
|
|
name = constructorModifier (Data.Text.pack (conName n))
|
|
|
|
extract u@(UnionLit name' e _)
|
|
| name == name' = fmap (L1 . M1) (extractL e)
|
|
| otherwise = fmap R1 (extractR u)
|
|
extract _ = Nothing
|
|
|
|
expected =
|
|
Union (Dhall.Map.insert name expectedL ktsR)
|
|
|
|
Type extractL expectedL = evalState (genericAutoWith options) 1
|
|
Type extractR expectedR = evalState (genericAutoWith options) 1
|
|
|
|
ktsR = unsafeExpectUnion "genericAutoWith (:+:)" expectedR
|
|
|
|
instance (GenericInterpret (f :+: g), GenericInterpret (h :+: i)) => GenericInterpret ((f :+: g) :+: (h :+: i)) where
|
|
genericAutoWith options = pure (Type {..})
|
|
where
|
|
extract e = fmap L1 (extractL e) <|> fmap R1 (extractR e)
|
|
|
|
expected = Union (Dhall.Map.union ktsL ktsR)
|
|
|
|
Type extractL expectedL = evalState (genericAutoWith options) 1
|
|
Type extractR expectedR = evalState (genericAutoWith options) 1
|
|
|
|
ktsL = unsafeExpectUnion "genericAutoWith (:+:)" expectedL
|
|
ktsR = unsafeExpectUnion "genericAutoWith (:+:)" expectedR
|
|
|
|
instance GenericInterpret f => GenericInterpret (M1 C c f) where
|
|
genericAutoWith options = do
|
|
res <- genericAutoWith options
|
|
pure (fmap M1 res)
|
|
|
|
instance GenericInterpret U1 where
|
|
genericAutoWith _ = pure (Type {..})
|
|
where
|
|
extract _ = Just U1
|
|
|
|
expected = Record (Dhall.Map.fromList [])
|
|
|
|
instance (GenericInterpret f, GenericInterpret g) => GenericInterpret (f :*: g) where
|
|
genericAutoWith options = do
|
|
Type extractL expectedL <- genericAutoWith options
|
|
Type extractR expectedR <- genericAutoWith options
|
|
let ktsL = unsafeExpectRecord "genericAutoWith (:*:)"expectedL
|
|
let ktsR = unsafeExpectRecord "genericAutoWith (:*:)"expectedR
|
|
pure
|
|
(Type
|
|
{ extract = liftA2 (liftA2 (:*:)) extractL extractR
|
|
, expected = Record (Dhall.Map.union ktsL ktsR)
|
|
}
|
|
)
|
|
|
|
getSelName :: Selector s => M1 i s f a -> State Int String
|
|
getSelName n = case selName n of
|
|
"" -> do i <- get
|
|
put (i + 1)
|
|
pure ("_" ++ show i)
|
|
nn -> pure nn
|
|
|
|
instance (Selector s, Interpret a) => GenericInterpret (M1 S s (K1 i a)) where
|
|
genericAutoWith opts@(InterpretOptions {..}) = do
|
|
name <- getSelName n
|
|
let extract (RecordLit m) = do
|
|
let name' = fieldModifier (Data.Text.pack name)
|
|
e <- Dhall.Map.lookup name' m
|
|
fmap (M1 . K1) (extract' e)
|
|
extract _ = Nothing
|
|
let expected =
|
|
Record (Dhall.Map.fromList [(key, expected')])
|
|
where
|
|
key = fieldModifier (Data.Text.pack name)
|
|
pure (Type {..})
|
|
where
|
|
n :: M1 i s f a
|
|
n = undefined
|
|
|
|
Type extract' expected' = autoWith opts
|
|
|
|
{-| An @(InputType a)@ represents a way to marshal a value of type @\'a\'@ from
|
|
Haskell into Dhall
|
|
-}
|
|
data InputType a = InputType
|
|
{ embed :: a -> Expr Src X
|
|
-- ^ Embeds a Haskell value as a Dhall expression
|
|
, declared :: Expr Src X
|
|
-- ^ Dhall type of the Haskell value
|
|
}
|
|
|
|
instance Contravariant InputType where
|
|
contramap f (InputType embed declared) = InputType embed' declared
|
|
where
|
|
embed' x = embed (f x)
|
|
|
|
{-| This class is used by `Interpret` instance for functions:
|
|
|
|
> instance (Inject a, Interpret b) => Interpret (a -> b)
|
|
|
|
You can convert Dhall functions with "simple" inputs (i.e. instances of this
|
|
class) into Haskell functions. This works by:
|
|
|
|
* Marshaling the input to the Haskell function into a Dhall expression (i.e.
|
|
@x :: Expr Src X@)
|
|
* Applying the Dhall function (i.e. @f :: Expr Src X@) to the Dhall input
|
|
(i.e. @App f x@)
|
|
* Normalizing the syntax tree (i.e. @normalize (App f x)@)
|
|
* Marshaling the resulting Dhall expression back into a Haskell value
|
|
-}
|
|
class Inject a where
|
|
injectWith :: InterpretOptions -> InputType a
|
|
default injectWith
|
|
:: (Generic a, GenericInject (Rep a)) => InterpretOptions -> InputType a
|
|
injectWith options
|
|
= contramap GHC.Generics.from (evalState (genericInjectWith options) 1)
|
|
|
|
{-| Use the default options for injecting a value
|
|
|
|
> inject = inject defaultInterpretOptions
|
|
-}
|
|
inject :: Inject a => InputType a
|
|
inject = injectWith defaultInterpretOptions
|
|
|
|
instance Inject Bool where
|
|
injectWith _ = InputType {..}
|
|
where
|
|
embed = BoolLit
|
|
|
|
declared = Bool
|
|
|
|
instance Inject Data.Text.Lazy.Text where
|
|
injectWith _ = InputType {..}
|
|
where
|
|
embed text =
|
|
TextLit (Chunks [] (Data.Text.Lazy.toStrict text))
|
|
|
|
declared = Text
|
|
|
|
instance Inject Text where
|
|
injectWith _ = InputType {..}
|
|
where
|
|
embed text = TextLit (Chunks [] text)
|
|
|
|
declared = Text
|
|
|
|
instance Inject Natural where
|
|
injectWith _ = InputType {..}
|
|
where
|
|
embed = NaturalLit
|
|
|
|
declared = Natural
|
|
|
|
instance Inject Integer where
|
|
injectWith _ = InputType {..}
|
|
where
|
|
embed = IntegerLit
|
|
|
|
declared = Integer
|
|
|
|
instance Inject Int where
|
|
injectWith _ = InputType {..}
|
|
where
|
|
embed = IntegerLit . toInteger
|
|
|
|
declared = Integer
|
|
|
|
instance Inject Word8 where
|
|
injectWith _ = InputType {..}
|
|
where
|
|
embed = IntegerLit . toInteger
|
|
|
|
declared = Integer
|
|
|
|
instance Inject Word16 where
|
|
injectWith _ = InputType {..}
|
|
where
|
|
embed = IntegerLit . toInteger
|
|
|
|
declared = Integer
|
|
|
|
instance Inject Word32 where
|
|
injectWith _ = InputType {..}
|
|
where
|
|
embed = IntegerLit . toInteger
|
|
|
|
declared = Integer
|
|
|
|
instance Inject Word64 where
|
|
injectWith _ = InputType {..}
|
|
where
|
|
embed = IntegerLit . toInteger
|
|
|
|
declared = Integer
|
|
|
|
instance Inject Double where
|
|
injectWith _ = InputType {..}
|
|
where
|
|
embed = DoubleLit
|
|
|
|
declared = Double
|
|
|
|
instance Inject () where
|
|
injectWith _ = InputType {..}
|
|
where
|
|
embed = const (RecordLit mempty)
|
|
|
|
declared = Record mempty
|
|
|
|
instance Inject a => Inject (Maybe a) where
|
|
injectWith options = InputType embedOut declaredOut
|
|
where
|
|
embedOut (Just x) =
|
|
OptionalLit declaredIn (pure (embedIn x))
|
|
embedOut Nothing =
|
|
OptionalLit declaredIn empty
|
|
|
|
InputType embedIn declaredIn = injectWith options
|
|
|
|
declaredOut = App Optional declaredIn
|
|
|
|
instance Inject a => Inject (Seq a) where
|
|
injectWith options = InputType embedOut declaredOut
|
|
where
|
|
embedOut xs = ListLit (Just declaredIn) (fmap embedIn xs)
|
|
|
|
declaredOut = App List declaredIn
|
|
|
|
InputType embedIn declaredIn = injectWith options
|
|
|
|
instance Inject a => Inject [a] where
|
|
injectWith = fmap (contramap Data.Sequence.fromList) injectWith
|
|
|
|
instance Inject a => Inject (Vector a) where
|
|
injectWith = fmap (contramap Data.Vector.toList) injectWith
|
|
|
|
instance Inject a => Inject (Data.Set.Set a) where
|
|
injectWith = fmap (contramap Data.Set.toList) injectWith
|
|
|
|
instance (Inject a, Inject b) => Inject (a, b)
|
|
|
|
{-| This is the underlying class that powers the `Interpret` class's support
|
|
for automatically deriving a generic implementation
|
|
-}
|
|
class GenericInject f where
|
|
genericInjectWith :: InterpretOptions -> State Int (InputType (f a))
|
|
|
|
instance GenericInject f => GenericInject (M1 D d f) where
|
|
genericInjectWith options = do
|
|
res <- genericInjectWith options
|
|
pure (contramap unM1 res)
|
|
|
|
instance GenericInject f => GenericInject (M1 C c f) where
|
|
genericInjectWith options = do
|
|
res <- genericInjectWith options
|
|
pure (contramap unM1 res)
|
|
|
|
instance (Constructor c1, Constructor c2, GenericInject f1, GenericInject f2) => GenericInject (M1 C c1 f1 :+: M1 C c2 f2) where
|
|
genericInjectWith options@(InterpretOptions {..}) = pure (InputType {..})
|
|
where
|
|
embed (L1 (M1 l)) =
|
|
UnionLit keyL (embedL l) (Dhall.Map.singleton keyR declaredR)
|
|
|
|
embed (R1 (M1 r)) =
|
|
UnionLit keyR (embedR r) (Dhall.Map.singleton keyL declaredL)
|
|
|
|
declared =
|
|
Union (Dhall.Map.fromList [(keyL, declaredL), (keyR, declaredR)])
|
|
|
|
nL :: M1 i c1 f1 a
|
|
nL = undefined
|
|
|
|
nR :: M1 i c2 f2 a
|
|
nR = undefined
|
|
|
|
keyL = constructorModifier (Data.Text.pack (conName nL))
|
|
keyR = constructorModifier (Data.Text.pack (conName nR))
|
|
|
|
InputType embedL declaredL = evalState (genericInjectWith options) 1
|
|
InputType embedR declaredR = evalState (genericInjectWith options) 1
|
|
|
|
instance (Constructor c, GenericInject (f :+: g), GenericInject h) => GenericInject ((f :+: g) :+: M1 C c h) where
|
|
genericInjectWith options@(InterpretOptions {..}) = pure (InputType {..})
|
|
where
|
|
embed (L1 l) =
|
|
UnionLit keyL valL (Dhall.Map.insert keyR declaredR ktsL')
|
|
where
|
|
(keyL, valL, ktsL') =
|
|
unsafeExpectUnionLit "genericInjectWith (:+:)" (embedL l)
|
|
embed (R1 (M1 r)) = UnionLit keyR (embedR r) ktsL
|
|
|
|
nR :: M1 i c h a
|
|
nR = undefined
|
|
|
|
keyR = constructorModifier (Data.Text.pack (conName nR))
|
|
|
|
declared = Union (Dhall.Map.insert keyR declaredR ktsL)
|
|
|
|
InputType embedL declaredL = evalState (genericInjectWith options) 1
|
|
InputType embedR declaredR = evalState (genericInjectWith options) 1
|
|
|
|
ktsL = unsafeExpectUnion "genericInjectWith (:+:)" declaredL
|
|
|
|
instance (Constructor c, GenericInject f, GenericInject (g :+: h)) => GenericInject (M1 C c f :+: (g :+: h)) where
|
|
genericInjectWith options@(InterpretOptions {..}) = pure (InputType {..})
|
|
where
|
|
embed (L1 (M1 l)) = UnionLit keyL (embedL l) ktsR
|
|
embed (R1 r) =
|
|
UnionLit keyR valR (Dhall.Map.insert keyL declaredL ktsR')
|
|
where
|
|
(keyR, valR, ktsR') =
|
|
unsafeExpectUnionLit "genericInjectWith (:+:)" (embedR r)
|
|
|
|
nL :: M1 i c f a
|
|
nL = undefined
|
|
|
|
keyL = constructorModifier (Data.Text.pack (conName nL))
|
|
|
|
declared = Union (Dhall.Map.insert keyL declaredL ktsR)
|
|
|
|
InputType embedL declaredL = evalState (genericInjectWith options) 1
|
|
InputType embedR declaredR = evalState (genericInjectWith options) 1
|
|
|
|
ktsR = unsafeExpectUnion "genericInjectWith (:+:)" declaredR
|
|
|
|
instance (GenericInject (f :+: g), GenericInject (h :+: i)) => GenericInject ((f :+: g) :+: (h :+: i)) where
|
|
genericInjectWith options = pure (InputType {..})
|
|
where
|
|
embed (L1 l) =
|
|
UnionLit keyL valL (Dhall.Map.union ktsL' ktsR)
|
|
where
|
|
(keyL, valL, ktsL') =
|
|
unsafeExpectUnionLit "genericInjectWith (:+:)" (embedL l)
|
|
embed (R1 r) =
|
|
UnionLit keyR valR (Dhall.Map.union ktsL ktsR')
|
|
where
|
|
(keyR, valR, ktsR') =
|
|
unsafeExpectUnionLit "genericInjectWith (:+:)" (embedR r)
|
|
|
|
declared = Union (Dhall.Map.union ktsL ktsR)
|
|
|
|
InputType embedL declaredL = evalState (genericInjectWith options) 1
|
|
InputType embedR declaredR = evalState (genericInjectWith options) 1
|
|
|
|
ktsL = unsafeExpectUnion "genericInjectWith (:+:)" declaredL
|
|
ktsR = unsafeExpectUnion "genericInjectWith (:+:)" declaredR
|
|
|
|
instance (GenericInject f, GenericInject g) => GenericInject (f :*: g) where
|
|
genericInjectWith options = do
|
|
InputType embedInL declaredInL <- genericInjectWith options
|
|
InputType embedInR declaredInR <- genericInjectWith options
|
|
|
|
let embed (l :*: r) =
|
|
RecordLit (Dhall.Map.union mapL mapR)
|
|
where
|
|
mapL =
|
|
unsafeExpectRecordLit "genericInjectWith (:*:)" (embedInL l)
|
|
|
|
mapR =
|
|
unsafeExpectRecordLit "genericInjectWith (:*:)" (embedInR r)
|
|
|
|
let declared = Record (Dhall.Map.union mapL mapR)
|
|
where
|
|
mapL = unsafeExpectRecord "genericInjectWith (:*:)" declaredInL
|
|
mapR = unsafeExpectRecord "genericInjectWith (:*:)" declaredInR
|
|
|
|
pure (InputType {..})
|
|
|
|
instance GenericInject U1 where
|
|
genericInjectWith _ = pure (InputType {..})
|
|
where
|
|
embed _ = RecordLit mempty
|
|
|
|
declared = Record mempty
|
|
|
|
instance (Selector s, Inject a) => GenericInject (M1 S s (K1 i a)) where
|
|
genericInjectWith opts@(InterpretOptions {..}) = do
|
|
name <- fieldModifier . Data.Text.pack <$> getSelName n
|
|
let embed (M1 (K1 x)) =
|
|
RecordLit (Dhall.Map.singleton name (embedIn x))
|
|
let declared =
|
|
Record (Dhall.Map.singleton name declaredIn)
|
|
pure (InputType {..})
|
|
where
|
|
n :: M1 i s f a
|
|
n = undefined
|
|
|
|
InputType embedIn declaredIn = injectWith opts
|
|
|
|
{-| The 'RecordType' applicative functor allows you to build a 'Type' parser
|
|
from a Dhall record.
|
|
|
|
For example, let's take the following Haskell data type:
|
|
|
|
> data Project = Project
|
|
> { projectName :: Text
|
|
> , projectDescription :: Text
|
|
> , projectStars :: Natural
|
|
> }
|
|
|
|
And assume that we have the following Dhall record that we would like to
|
|
parse as a @Project@:
|
|
|
|
> { name =
|
|
> "dhall-haskell"
|
|
> , description =
|
|
> "A configuration language guaranteed to terminate"
|
|
> , stars =
|
|
> 289
|
|
> }
|
|
|
|
Our parser has type 'Type' @Project@, but we can't build that out of any
|
|
smaller parsers, as 'Type's cannot be combined (they are only 'Functor's).
|
|
However, we can use a 'RecordType' to build a 'Type' for @Project@:
|
|
|
|
> project :: Type Project
|
|
> project =
|
|
> record
|
|
> ( Project <$> field "name" string
|
|
> <*> field "description" string
|
|
> <*> field "stars" natural
|
|
> )
|
|
|
|
-}
|
|
|
|
newtype RecordType a =
|
|
RecordType
|
|
( Data.Functor.Product.Product
|
|
( Control.Applicative.Const
|
|
( Dhall.Map.Map
|
|
Text
|
|
( Expr Src X )
|
|
)
|
|
)
|
|
( Data.Functor.Compose.Compose
|
|
( (->) ( Expr Src X ) )
|
|
Maybe
|
|
)
|
|
a
|
|
)
|
|
deriving (Functor, Applicative)
|
|
|
|
|
|
-- | Run a 'RecordType' parser to build a 'Type' parser.
|
|
record :: RecordType a -> Dhall.Type a
|
|
record ( RecordType ( Data.Functor.Product.Pair ( Control.Applicative.Const fields ) ( Data.Functor.Compose.Compose extractF ) ) ) =
|
|
Type
|
|
{ extract =
|
|
extractF
|
|
, expected =
|
|
Record fields
|
|
}
|
|
|
|
|
|
-- | Parse a single field of a record.
|
|
field :: Text -> Type a -> RecordType a
|
|
field key valueType =
|
|
let
|
|
extractBody expr = do
|
|
RecordLit fields <-
|
|
return expr
|
|
|
|
Dhall.Map.lookup key fields
|
|
>>= extract valueType
|
|
|
|
in
|
|
RecordType
|
|
( Data.Functor.Product.Pair
|
|
( Control.Applicative.Const
|
|
( Dhall.Map.singleton
|
|
key
|
|
( Dhall.expected valueType )
|
|
)
|
|
)
|
|
( Data.Functor.Compose.Compose extractBody )
|
|
)
|
|
|
|
{-| The 'UnionType' monoid allows you to build a 'Type' parser
|
|
from a Dhall union
|
|
|
|
For example, let's take the following Haskell data type:
|
|
|
|
> data Status = Queued Natural
|
|
> | Result Text
|
|
> | Errored Text
|
|
|
|
And assume that we have the following Dhall union that we would like to
|
|
parse as a @Status@:
|
|
|
|
> < Result = "Finish succesfully"
|
|
> | Queued : Natural
|
|
> | Errored : Text
|
|
> >
|
|
|
|
Our parser has type 'Type' @Status@, but we can't build that out of any
|
|
smaller parsers, as 'Type's cannot be combined (they are only 'Functor's).
|
|
However, we can use a 'UnionType' to build a 'Type' for @Status@:
|
|
|
|
> status :: Type Status
|
|
> status =
|
|
> union
|
|
> ( Queued <$> constructor "Queued" natural
|
|
> <> Result <$> constructor "Result" string
|
|
> <> Errored <$> constructor "Errored" string
|
|
> )
|
|
|
|
-}
|
|
newtype UnionType a =
|
|
UnionType
|
|
( Data.Functor.Compose.Compose (Dhall.Map.Map Text) Type a )
|
|
deriving (Functor)
|
|
|
|
instance Data.Semigroup.Semigroup (UnionType a) where
|
|
(<>) = coerce ((<>) :: Dhall.Map.Map Text (Type a) -> Dhall.Map.Map Text (Type a) -> Dhall.Map.Map Text (Type a))
|
|
|
|
instance Monoid (UnionType a) where
|
|
mempty = coerce (mempty :: Dhall.Map.Map Text (Type a))
|
|
mappend = (Data.Semigroup.<>)
|
|
|
|
-- | Run a 'UnionType' parser to build a 'Type' parser.
|
|
union :: UnionType a -> Type a
|
|
union (UnionType (Data.Functor.Compose.Compose mp)) = Type
|
|
{ extract = extractF
|
|
, expected = Union expect
|
|
}
|
|
where
|
|
expect = Dhall.expected <$> mp
|
|
extractF e0 = do
|
|
UnionLit fld e1 rest <- Just e0
|
|
t <- Dhall.Map.lookup fld mp
|
|
guard $ rest == Dhall.Map.delete fld expect
|
|
Dhall.extract t e1
|
|
|
|
-- | Parse a single constructor of a union
|
|
constructor :: Text -> Type a -> UnionType a
|
|
constructor key valueType = UnionType
|
|
( Data.Functor.Compose.Compose (Dhall.Map.singleton key valueType) )
|
|
|
|
{-| The 'RecordInputType' divisible (contravariant) functor allows you to build
|
|
an 'InputType' injector for a Dhall record.
|
|
|
|
For example, let's take the following Haskell data type:
|
|
|
|
> data Project = Project
|
|
> { projectName :: Text
|
|
> , projectDescription :: Text
|
|
> , projectStars :: Natural
|
|
> }
|
|
|
|
And assume that we have the following Dhall record that we would like to
|
|
parse as a @Project@:
|
|
|
|
> { name =
|
|
> "dhall-haskell"
|
|
> , description =
|
|
> "A configuration language guaranteed to terminate"
|
|
> , stars =
|
|
> 289
|
|
> }
|
|
|
|
Our injector has type 'InputType' @Project@, but we can't build that out of any
|
|
smaller injectors, as 'InputType's cannot be combined (they are only 'Contravariant's).
|
|
However, we can use an 'InputRecordType' to build an 'InputType' for @Project@:
|
|
|
|
> injectProject :: InputType Project
|
|
> injectProject =
|
|
> inputRecord
|
|
> ( adapt >$< inputFieldWith "name" inject
|
|
> >*< inputFieldWith "description" inject
|
|
> >*< inputFieldWith "stars" inject
|
|
> )
|
|
> where
|
|
> adapt (Project{..}) = (projectName, (projectDescription, projectStars))
|
|
|
|
Or, since we are simply using the `Inject` instance to inject each field, we could write
|
|
|
|
> injectProject :: InputType Project
|
|
> injectProject =
|
|
> inputRecord
|
|
> ( adapt >$< inputField "name"
|
|
> >*< inputField "description"
|
|
> >*< inputField "stars"
|
|
> )
|
|
> where
|
|
> adapt (Project{..}) = (projectName, (projectDescription, projectStars))
|
|
|
|
-}
|
|
|
|
-- | Infix 'divided'
|
|
(>*<) :: Divisible f => f a -> f b -> f (a, b)
|
|
(>*<) = divided
|
|
|
|
infixr 5 >*<
|
|
|
|
newtype RecordInputType a
|
|
= RecordInputType (Dhall.Map.Map Text (InputType a))
|
|
|
|
instance Contravariant RecordInputType where
|
|
contramap f (RecordInputType inputTypeRecord) = RecordInputType $ contramap f <$> inputTypeRecord
|
|
|
|
instance Divisible RecordInputType where
|
|
divide f (RecordInputType bInputTypeRecord) (RecordInputType cInputTypeRecord) =
|
|
RecordInputType
|
|
$ Dhall.Map.union
|
|
((contramap $ fst . f) <$> bInputTypeRecord)
|
|
((contramap $ snd . f) <$> cInputTypeRecord)
|
|
conquer = RecordInputType mempty
|
|
|
|
inputFieldWith :: Text -> InputType a -> RecordInputType a
|
|
inputFieldWith name inputType = RecordInputType $ Dhall.Map.singleton name inputType
|
|
|
|
inputField :: Inject a => Text -> RecordInputType a
|
|
inputField name = inputFieldWith name inject
|
|
|
|
inputRecord :: RecordInputType a -> InputType a
|
|
inputRecord (RecordInputType inputTypeRecord) = InputType makeRecordLit recordType
|
|
where
|
|
recordType = Record $ declared <$> inputTypeRecord
|
|
makeRecordLit x = RecordLit $ (($ x) . embed) <$> inputTypeRecord
|
|
|
|
{-| The 'UnionInputType' monoid allows you to build
|
|
an 'InputType' injector for a Dhall record.
|
|
|
|
For example, let's take the following Haskell data type:
|
|
|
|
> data Status = Queued Natural
|
|
> | Result Text
|
|
> | Errored Text
|
|
|
|
And assume that we have the following Dhall union that we would like to
|
|
parse as a @Status@:
|
|
|
|
> < Result = "Finish succesfully"
|
|
> | Queued : Natural
|
|
> | Errored : Text
|
|
> >
|
|
|
|
Our injector has type 'InputType' @Status@, but we can't build that out of any
|
|
smaller injectors, as 'InputType's cannot be combined.
|
|
However, we can use an 'InputUnionType' to build an 'InputType' for @Status@:
|
|
|
|
> injectStatus :: InputType Status
|
|
> injectStatus =
|
|
> adapt
|
|
> >$< inputConstructorWith "Queued" inject
|
|
> >|< inputConstructorWith "Result" inject
|
|
> >|< inputConstructorWith "Errored" inject
|
|
> where
|
|
> adapt (Queued n) = Left (Left n)
|
|
> adapt (Result t) = Left (Right t)
|
|
> adapt (Errored e) = Right e
|
|
|
|
Or, since we are simply using the `Inject` instance to inject each branch, we could write
|
|
|
|
> injectStatus :: InputType Status
|
|
> injectStatus =
|
|
> adapt
|
|
> >$< inputConstructor "Queued"
|
|
> >|< inputConstructor "Result"
|
|
> >|< inputConstructor "Errored"
|
|
> where
|
|
> adapt (Queued n) = Left (Left n)
|
|
> adapt (Result t) = Left (Right t)
|
|
> adapt (Errored e) = Right e
|
|
-}
|
|
newtype UnionInputType a =
|
|
UnionInputType
|
|
( Data.Functor.Product.Product
|
|
( Control.Applicative.Const
|
|
( Dhall.Map.Map
|
|
Text
|
|
( Expr Src X )
|
|
)
|
|
)
|
|
( Op (Text, Expr Src X) )
|
|
a
|
|
)
|
|
deriving (Contravariant)
|
|
|
|
-- | Combines two 'UnionInputType' values. See 'UnionInputType' for usage
|
|
-- notes.
|
|
--
|
|
-- Ideally, this matches 'Data.Functor.Contravariant.Divisible.chosen';
|
|
-- however, this allows 'UnionInputType' to not need a 'Divisible' instance
|
|
-- itself (since no instance is possible).
|
|
(>|<) :: UnionInputType a -> UnionInputType b -> UnionInputType (Either a b)
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UnionInputType (Data.Functor.Product.Pair (Control.Applicative.Const mx) (Op fx))
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>|< UnionInputType (Data.Functor.Product.Pair (Control.Applicative.Const my) (Op fy)) =
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UnionInputType
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( Data.Functor.Product.Pair
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( Control.Applicative.Const (mx <> my) )
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( Op (either fx fy) )
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)
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infixr 5 >|<
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inputUnion :: UnionInputType a -> InputType a
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inputUnion ( UnionInputType ( Data.Functor.Product.Pair ( Control.Applicative.Const fields ) ( Op embedF ) ) ) =
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InputType
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{ embed = \x ->
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let (name, y) = embedF x
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in UnionLit name y (Dhall.Map.delete name fields)
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, declared =
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Union fields
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}
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inputConstructorWith
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:: Text
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-> InputType a
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-> UnionInputType a
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inputConstructorWith name inputType = UnionInputType $
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Data.Functor.Product.Pair
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( Control.Applicative.Const
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( Dhall.Map.singleton
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name
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( declared inputType )
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)
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)
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( Op ( (name,) . embed inputType )
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)
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inputConstructor
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:: Inject a
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=> Text
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-> UnionInputType a
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inputConstructor name = inputConstructorWith name inject
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