The Haskell implementation was not matching the specification for
type-checking union types:
* The inferred type of union types was (incorrectly) always returning `Type`
* Unions of mixed alternative types were not being properly rejected
I also discovered several mistakes in the error messages, which I fixed along
the way.
... as standardized in https://github.com/dhall-lang/dhall-lang/pull/307
Note that this a breaking change because:
* Newlines are now mandatory after the opening `''` of a multi-line
literal
* The spaces before the trailing `''` count towards the leading
indentation computation
* Test with QuickCheck that an expression is always the same as itself
I noticed cases where the diffing code returns that an expression is not the
same as itself (for example, an empty list). This commit adds a QuickCheck test
to illustrate it, and maybe other cases.
Sadly, I had to expose some internals from Dhall.Diff for the test, which makes
the interface less nice.
* Fix diff so that an empty list is the same as itself
This adds three new Nix build products:
* `try-dhall-static` - The static assets for "Try Dhall"
* `try-dhall-server` - A script which serves the static assets for local
debugging
* `tarball-try-dhall` - A tarball of the static assets
This is powered by a new small `dhall-try` package which is also included
in this change.
* Autocomplete repl commands
* Autocomplete imports (file and environment)
* Improve autocomplete separators
* Autocomplete records fields
* Remove use of TypeApplications
* Improve file path completion
* Autocomplete union alternatives
* Import missing (<>)
* Improve parsing of assignment in repl commands
* Remove no-longer-used `foldl'`
* Fix record field autocomplete and improve command autocomplete
* Fix definition order in repl environment
* Autocomplete variables in scope and all reserved identifiers
The motivation for this change is so that more code type-checks
within a REPL session.
For example, before this change the following session fails:
```haskell
⊢ :let Either = λ(a : Type) → λ(b : Type) → < Left : a | Right : b >
⊢ :let Example = < Left : Natural | Right : Bool >
Example : Type
⊢ Example.Left
Example : Type
Error: Not a record or a union
Example.Left
(stdin):1:1
```
After this change, the same session works:
```
[⊢ :let Example = < Left : Natural | Right : Bool >
Example : Type
⊢ Example.Left
λ(Left : Natural) → < Left = Left | Right : Bool >
```
The difference is in how we incorporate prior definitions when
type-checking code. Before this change prior definitions were added
to the context, which leads to type-checking failures because type
synonyms don't work when used in this way. After this change we
incorporate them as extra `let` definitions (same as normalization).
This is essentially a revert of 25d86e8e5d
The primary motivation for this is so that paths beginning with `../`
don't get reformatted to begin `./../`.
The secondary motivation for this is to more closely match the standard.
There are fewer special cases in the logic if there is a dedicated
constructor for the `Parent` case.
Fixes#714
This adds a `--json` flag that `dhall decode` and `dhall encode` can use to
read/write the equivalent JSON representation of the CBOR. This comes in
handy for the parsing compliance tests which use this CBOR-as-JSON as the
standard representation of the abstract syntax tree.
Now that `constructors x` is the same as `x` we can have `dhall lint`
safely strip all uses of `constructors` in preparation for removing the
keyword entirely.
Fixes#509
The `Dhall.Import.HTTP` module had logic for pretty-printing HTTP error
message, but this logic wasn't being used anywhere! This change fixes
that and also polishes the error messages a little bit.
* Add dotgen as a dependency
Signed-off-by: Basile Henry <bjm.henry@gmail.com>
* Build up dot graph while resolving imports
Signed-off-by: Basile Henry <bjm.henry@gmail.com>
* Add --dot option to resolve in CLI
Signed-off-by: Basile Henry <bjm.henry@gmail.com>
* Handle diamond dependencies in dot graph
* Refactor dot graph generation
This fixes an apparently very old bug in import caching caught by @basile-henry
Before this change the import resolution algorithm was:
1. Retrieving the cache
2. Transitively resolving all imports
3. Setting the new cache to be current import insert into the cache retrieved in
step 1
The bug is that all of the transitive imports resolved in step 2 added
entries of their own to the cache and those new cache entries were being
clobbered by step 3.
The fix is simple: don't use the cache retrieved in step 1 to compute
the updated cache in step 3. Rather, use `modify` instead of `put` to
create the new cache so that we preserve newly-added cache entries.
`dhall lint` was incorrectly deleting `let` bindings that are being used
due to not checking other `let` bindings within the same multi-`let`
expression for free variable occurrences.
This change fixes that and adds the first regression test for `dhall
lint`
Fixes#692
The standard permits a user to access a constructor from a type stored inside
a record, but the Haskell implementation had a mistake which prevented this.
Specifically, the Haskell implementation was not normalizing the union type
as the standard specified before attempting to access the constructor, leading
to an unexpected type error.
Fixes https://github.com/dhall-lang/dhall-lang/issues/267
According to the standard, Unicode characters up to `0x10FFFF` do not
require escaping. See:
33cab24f8e/standard/dhall.abnf (L192)
... so we can preserve them when pretty-printing Dhall expressions.
Note that the current code still does not comply with the standard for Unicode
characters beyond `0x10FFFF`, but I'll defer fixing that to a subsequent
change.
The issue was that the parser was attempting to parse // first, which
will succeed on the prefix of //\\, then the parser will get an error
because it expects a sub expression but the input is \\.
The motivation for this change is:
* To catch build failures in downstream packages whenever we make a breaking
change to the `dhall` API
* To reduce the amount of work I need in order to cut a release for all of
these packages
* To better share Nix/CI-related logic between the projects
Note that I have not yet migrated `dhall-nix` in. I'm waiting for
https://github.com/dhall-lang/dhall-nix/issues/17 to be fixed since
`dhall-nix` is incompatible with later versions of `megaparsec` due to
`hnix`.
