https://github.com/the-sett/elm-pretty-printer

https://github.com/the-sett/elm-pretty-printer

Last synced: about 1 month ago
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• Host: GitHub
• URL: https://github.com/the-sett/elm-pretty-printer
• Owner: the-sett
• License: bsd-3-clause
• Created: 2017-12-18T16:02:29.000Z (over 6 years ago)
• Default Branch: master
• Last Pushed: 2023-10-25T11:30:48.000Z (8 months ago)
• Last Synced: 2024-05-18T20:48:14.135Z (about 1 month ago)
• Language: Elm
• Size: 115 KB
• Stars: 11
• Watchers: 2
• Forks: 3
• Open Issues: 3
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Lists

• awesome-elm-pltd - the-sett/elm-pretty-printer - A pretty printing library based on 'A Prettier Printer' by Philip Wadler. (Packages / Code Generation)

README

        
**Contacts for Support**

- @rupertlssmith on https://elmlang.slack.com

- @rupert on https://discourse.elm-lang.org

**Status**

- 06-Oct-2020 - Published as version 3.0.0

A type parameter has been added to `Doc` allowing `String`s in the document to

be *tagged*. Tagged strings can then be rendered with the new `Pretty.Renderer`

module, for syntax highlighting.

The new `Pretty.Renderer` module, also makes it possible to generate non-`String`

output formats, for example HTML.

# elm-pretty-printer

A pretty printing library based on ['A Prettier Printer' by Philip Wadler](https://homepages.inf.ed.ac.uk/wadler/papers/prettier/prettier.pdf).

This version follows Wadler's paper closely, but is actually ported from a Haskell

implementation that is referred to as Wadler/Leijen. Leijen added Column and Nesting

constructors in the document type, which make for easier and more flexible indentation.

I have added the ability to have different ways of joining documents when placing them

on the same line, or breaking them into multiple lines. When placed within a `group`

, the usual `line` function will render as a line break or a space; the `tightline`

will render as a line break or "". The `separators` function allows a string to be

given that is placed between docs on the same line, or after the start of the line

when placing on multiple lines - useful when rendering commas in a list at the start

of the line.

This implementation is usually sufficiently lazy and tail-recursive to perform well

under Elm. Occassionally an exponential blow-up can happen if the `softline` function

is not used carefully. Plase raise a GitHub issue on this if it is not performing well

enough for you.

# Syntax Highlighting and rendering to HTML

The `Pretty.Renderer` module allows for finer control over how the output is produced.

This requires a `Renderer` specification to be set up that provides

call-back functions that will be used when tagged strings in the document are

encountered, and also at line ends.

This is left folded over the output using whatever accumulator type you need in order to transform the output.