https://github.com/ayazhafiz/strictly-annotated

A pretty printer with special support for comment-like annotations
https://github.com/ayazhafiz/strictly-annotated

Last synced: 2 months ago
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A pretty printer with special support for comment-like annotations

• Host: GitHub
• URL: https://github.com/ayazhafiz/strictly-annotated
• Owner: ayazhafiz
• Created: 2021-06-17T19:15:17.000Z (over 3 years ago)
• Default Branch: base
• Last Pushed: 2021-06-28T20:10:02.000Z (over 3 years ago)
• Last Synced: 2024-05-02T02:22:24.847Z (8 months ago)
• Language: OCaml
• Size: 16.6 KB
• Stars: 0
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# Strictly Annotated

Strictly Annotated is a pretty-printer derived from [Strictly Pretty](http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.34.2200) (Lindig 2000).

See below for a small introduction, or [this blog post](https://ayazhafiz.com/articles/21/strictly-annotated) for a detailed design.

Or just read the source, it's quite short.

The contribution of this package is pretty-printing in the presence of

annotations, which can be thought of comments in source code or some kind of

supplemental information that is in some sense less important than other terms

in a document. Terms of the document are pretty-printed in the usual way, and

annotations are formatted so as to be highly visible without interfering with

the document's terms.

For example, given the source

```

if a == b then a << 2 else a + b

```

with annotations attached on the terms `if`, `then`, and `else`, Strictly

Annotated may format this document as

```

if a == b    # new conditional

then a << 2  # true branch

else a + b   # false branch

```

or at a narrower width,

```

if  # new conditional

  a == b

then  # true branch

  a << 2

else  # false branch

  a + b

```

## History and Citations

As mentioned, this printer is derived from Lindig's [Strictly

Pretty](http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.34.2200).

Strictly Pretty is derived from [A prettier printer](https://homepages.inf.ed.ac.uk/wadler/papers/prettier/prettier.pdf) (Walder, 1999),

which in turn was influenced by [The Design of a Pretty-printing Library](http://belle.sourceforge.net/doc/hughes95design.pdf) (Hughes, 1995).

Both Hughes and Walder embraced the formalization of an algebra for

pretty-printing, proving equational laws of pretty-printing combinators in

their implementations. An algebra of pretty-printing is both easy to express and

yields an efficient implementation in a lazy language like Haskell. Laziness is

important, because pretty-printing inevitably involves expanding some layout

choices to determine which is "the best" - having to eagerly expand all layout

choices would be a non-starter. Lindig was aware of this issue, and in his note

_Strictly Prettier_ attempted to translate the main ideas involved in Walder's

pretty-printing system for use in an eager execution.

Variants of these systems are used in the Haskell, OCaml, and Elixir standard

libraries, among others.