https://github.com/thesephist/inkfmt
Code formatter for the Ink programming language
https://github.com/thesephist/inkfmt
code-formatter ink recursive-descent-parser
Last synced: 17 days ago
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Code formatter for the Ink programming language
- Host: GitHub
- URL: https://github.com/thesephist/inkfmt
- Owner: thesephist
- License: mit
- Created: 2020-05-01T01:50:53.000Z (almost 5 years ago)
- Default Branch: master
- Last Pushed: 2020-12-20T17:14:09.000Z (over 4 years ago)
- Last Synced: 2025-03-24T18:49:39.608Z (about 1 month ago)
- Topics: code-formatter, ink, recursive-descent-parser
- Language: Shell
- Size: 136 KB
- Stars: 7
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# inkfmt 🖋
**inkfmt** (pronounced "ink format") is a self-hosting code formatter for the [Ink programming language](https://dotink.co/). It's written in Ink itself, and designed to be run before commits to canonicalize syntax and whitespace, but still respects the code author's line breaks and comments. It's a work in progress, but gives the expected output for 95% of cases today.
All Ink code in this project is, of course, formatted with inkfmt. You can read an in-depth review of inkfmt's design and implementation in the [inkfmt post on the Ink blog](https://dotink.co/posts/inkfmt/).
inkfmt makes these transformations:
- Remove unnecessary commas
- At ends of lines (Ink has automatic comma insertion at line endings)
```
a := 1, a := 1
b := 2, -> b := 2
c := a + b, c := a + b
```
- At end of expression and argument lists
```
result := f(1, 2, [3, 4, ], {
key: val,
}, )
->
result := f(1, 2, [3, 4], {
key: val
})
```
- Canonicalize whitespaces
- Sensibly auto-indent lines
```
func := n => even?(n) :: {
true -> 'is' +
' even'
false -> 'is odd'
}
->
func := n => even?(n) :: {
true -> 'is' +
' even'
false -> 'is odd
}
```
- Ensure single spaces between specific tokens, when appropriate
```
func := (x,y)=> pow(x,2)+3.1415
->
func := (x, y) => pow(x, 2) + 3.1415
```
inkfmt intentionally avoids certain kinds of code transformations that might be disruptive to the intent of the code author.
- inkfmt doesn't **change line breaks** in code. Many other formatters like [Prettier](https://prettier.io) and [rustfmt](https://github.com/rust-lang/rustfmt) break lines according to some length heuristic, while others like [gofmt](https://golang.org/cmd/gofmt/) do not. I personally prefer formatters not to mess with my line breaks. Line breaks often convey important information, grouping arguments or list entries together in semantically important ways. If a line gets too long, I can manually break it in a sensible place. It might also be an indicator that there might be a better way to describe what I'm doing in code.
- inkfmt doesn't **add or remove idempotent parentheses**. Some more strict and deterministic formatters like [Prettier](https://prettier.io) will add and remove parentheses around expressions to disambiguate expressions or add consistency, but like line breaks, I think programmers use parentheses to group things in meaningful ways or make the code more readable, and formatters should clean them up, not remove them.
## Usage
At this point, the `fmt` program reads Ink code in from `stdin` and writes formatted code and/or errors out to `stdout`. Eventually, the goal will be for the executable to read a tree of files and format all Ink programs within.
With Ink installed, we can simply run:
```sh
./fmt.ink < input.ink > output.ink
```
## References and further reading
- Phil Wadler's [Prettier Printer](https://homepages.inf.ed.ac.uk/wadler/papers/prettier/prettier.pdf)
- Prettier's JavaScript implementation of the above, [GitHub](https://github.com/prettier/prettier-printer)
- Go's implementation of [gofmt](https://golang.org/src/cmd/gofmt/doc.go)