mirror of
https://github.com/google/ormolu.git
synced 2024-09-11 08:05:24 +03:00
71 lines
2.8 KiB
Markdown
71 lines
2.8 KiB
Markdown
|
# Contributing
|
||
|
|
|
||
|
|
Issues (bugs, feature requests or otherwise feedback) may be reported in
|
||
|
|
[the GitHub issue tracker for this
|
||
|
|
project](https://github.com/tweag/ormolu/issues). Pull requests are also
|
||
|
|
welcome.
|
||
|
|
|
||
|
|
When contributing to this repository, please first discuss the change you
|
||
|
|
wish to make via an issue, unless it's entirely trivial (typo fixes, etc.).
|
||
|
|
If there is already an issue that describes the change you have in mind,
|
||
|
|
comment on it indicating that you're going to work on that. This way we can
|
||
|
|
avoid the situation when several people work on the same thing.
|
||
|
|
|
||
|
|
Please make sure that all non-trivial changes are described in commit
|
||
|
|
messages and PR descriptions.
|
||
|
|
|
||
|
|
## What to hack on?
|
||
|
|
|
||
|
|
Right now there are two options for people who want to contribute:
|
||
|
|
|
||
|
|
* [Implementing rendering of AST][cover-ast]. This is the main focus right
|
||
|
|
now because we want to have a MVP which can render all syntactical
|
||
|
|
constructions found in Haskell source code. Once that is achieved we'll
|
||
|
|
polish the tool iteratively.
|
||
|
|
* [Fixing bugs][bugs]. If this seems more interesting than implementing
|
||
|
|
rendering of AST, you are welcome to do this as well.
|
||
|
|
|
||
|
|
## Implementing rendering of AST
|
||
|
|
|
||
|
|
The `Ormolu.Printer.Combinators` module provides a DSL for rendering of GHC
|
||
|
|
AST. You'll probably only need this one module for writing new rendering
|
||
|
|
functions. The module documents how to use the printing combinators it
|
||
|
|
provides. Consult the Haddocks to learn more about them.
|
||
|
|
|
||
|
|
Create new modules corresponding to the things you want to render under
|
||
|
|
`Ormolu.Printer.Meat`. For example, there are `Ormolu.Printer.Meat.Type` and
|
||
|
|
`Ormolu.Printer.Meat.Declaration.Data`.
|
||
|
|
|
||
|
|
Concrete rendering functions get their names by appending `p_` to the name
|
||
|
|
of the type which describes a particular part of AST. For example, the
|
||
|
|
function for rendering types is correspondingly:
|
||
|
|
|
||
|
|
```haskell
|
||
|
|
p_hsType :: HsType GhcPs -> R ()
|
||
|
|
```
|
||
|
|
|
||
|
|
In general rendering functions like this take 1 or more arguments and
|
||
|
|
produce `R ()` which is a rendering action.
|
||
|
|
|
||
|
|
### Testing
|
||
|
|
|
||
|
|
Testing has been taken good care of and now it amounts to just adding
|
||
|
|
examples under `data/examples`. Each example is a pair of files:
|
||
|
|
`<example-name>.hs` for input and `<example-name>-out.hs` for corresponding
|
||
|
|
expected output.
|
||
|
|
|
||
|
|
Testing is performed as following:
|
||
|
|
|
||
|
|
* Given snippet of source code is parsed and pretty-printed.
|
||
|
|
* The result of printing is parsed back again and the AST is compared to the
|
||
|
|
AST obtained from the original file. They should match.
|
||
|
|
* The output of printer is checked against the expected output.
|
||
|
|
* Idempotency property is verified: formatting already formatted code
|
||
|
|
results in exactly the same output.
|
||
|
|
|
||
|
|
Examples can be organized in sub-directories, see the existing ones for
|
||
|
|
inspiration.
|
||
|
|
|
||
|
|
[cover-ast]: https://github.com/tweag/ormolu/issues?q=is%3Aissue+is%3Aopen+label%3Acovering-ghc-ast
|
||
|
|
[bugs]: https://github.com/tweag/ormolu/issues?q=is%3Aissue+is%3Aopen+label%3Abug
|