Fixes#832 832
This includes two changes:
* Fix a missing newline at the end of `dhall format` output when not using
the `--inplace` option
* Better align ASCII output
.. as caught by @Profpatsch in:
https://github.com/dhall-lang/dhall-haskell/pull/812#issuecomment-462134701
Before this change the location was always being reported as `(stdin):1:1`
because the `SourcedException` kept getting modified with a broader
source location in the `Note` branch of `loadWith`.
This was originally done so that alternative imports would show the entire
source span, but it mistakenly just kept bubbling up regardless of whether or
not there were alternative imports.
Instead, this includes an approximate source span for alternative imports.
The source span bounds are correct but the contents just show which imports
were alternated, even if they might have been buried in a larger expression.
For example, if the original expression had been:
```haskell
Some ./x ? None ./y
```
... then the source span for the error message would display just:
```haskell
./x ? ./y
```
... which is probably as good as it will get for now.
The format for the save file is a plain Dhall file containing REPL commands.
This will hopefully mean that the save file can be edited manually if need be
without too much effort.
Signed-off-by: Basile Henry <bjm.henry@gmail.com>
The motivation behind this change is so that users can freeze remote imports
(like the Prelude) but ignore local imports so that subsequent runs of the
interpreter reflect changes to local files and environment variables.
The reasoning behind this is that there are two primary benefits of integrity
checks:
* Improved security
* Caching
... and one downside which is that updates to those imports are not pulled in
until the integrity check is updated or removed.
However, environment variables and local file paths do not benefit from
improved security or caching, so there is only a downside to freezing them.
Specifically:
* Environment variables and local file paths are both cheap to resolve
... so they don't really benefit from caching.
To be precise, they *could* benefit from caching if the cache expression is
cheaper to parse and normalize compared to the original file. For those
cases there is still an `--all` flag to freeze all imports.
* Environment variables and local file paths are trusted
For example, when a user runs the `dhall` executable they are implicitly
trusting their filesystem which provides that executable. Similarly, when
they run `dhall` without an absolute path they are implicitly trusting that
their `PATH` environment variable has not been compromised to point to a
malicious executable.
Up until now, Dhall's threat model has always been that local imports are
trusted but remote imports are not, so this is consistent with that threat
model.
... so as far as environment variables and local files are concerned there are
only downsides to freezing them and no up-side. This is why this change
no longer freezes them.
This also renames `hashImport` to `freezeImport` for more terminology
consistency.
This is useful for integrating dhall to build systems where dhall
expressions (e.g. of type `Text`) are build products.
This also renames the `--list` flag to `--transitive-dependencies`
Fixes https://github.com/dhall-lang/dhall-lang/issues/357
This uses `Text.Megaparsec.Char.Lexer.decimal` which matches the Dhall
grammar. The previous `decimal` parser was also accepting non-standard
hex and octal literals.
This commit adds a flag for producing a machine readable listing of
dependencies of a dhall expression.
This flag can be used to integrate dhall more easily to file watchers or
build systems which require such lists of dependencies.
`dhall lint` would fail on the following expression:
```
let replicate = https://prelude.dhall-lang.org/List/replicate
in let Config = { name : Text, age : Natural }
in let Configs = List Config
in replicate 10 Text "!"
```
... because the code (incorrectly) assumed that simplifying an inner
`let` binding would preserve at least one `let` binding. However, when the
outer `let` (beginning with `let replicate`) is simplified the inner `let`
(beginning with `let Config`) simplifies down to just `replicate 10 Text "!"`
which has no `let` binding at all, leading to a pattern match failure.
This change fixes that by extending the code to correctly handle that case
with an exhaustive pattern match.
Related to: https://github.com/dhall-lang/dhall-lang/issues/343
According to the standard a non-empty list with a type annotation should
not be encoded with the type annotation alongside the list elements. The
type annotation should be parsed and encoded as a separate constructor.
A refactor of the Nix build accidentally removed the `-Werror` flag, which
caused some warnings to get past CI. This change fixes that and removes the
warnings.
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.
Several people commented that they had difficulty with the first example:
* They didn't realize that the mistake was supposed to be typo because they
never found it
* They didn't realize they were supposed to progress to the next tab
This changes fixes those two issues
