oppi.li
write literate haskell programs in typst
cdn.oppi.li/typst-unlit.pdf
haskell
typst
regen readme
Signed-off-by: oppiliappan <me@oppi.li>
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readme.md
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readme.md
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# Typst-Unlit
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Write literate Haskell programs in Typst
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*[tangled.org/@oppi.li/typst-unlit](https://tangled.org/@oppi.li/typst-unlit)*
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*Serves: 1 Prep Time: 10min Compile Time: 10ms*
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**Serves: 1 Prep Time: 10min Compile Time: 10ms**
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A literate program is one where comments are first-class citizens, and
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code is explicitly demarcated, as opposed to a regular program, where
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preprocessor to extract code from documents. This preprocessor is known
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as *unlit*[^1]. GHC also supports *custom* preprocessors, which can be
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passed in via the `-pgmL` flag. This very document you are reading, is
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one such preprocessor that allows embedding Haskell code inside typst
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files[^2].
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one such preprocessor program that allows extracting Haskell from Typst
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code (although it has been rendered to HTML, PDF or markdown depending
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on where you are reading it)[^2]!
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This recipe not only gives you a fish (the typst-unlit preprocessor),
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but also, teaches you how to fish (write your own preprocessors).
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with an empty line! To detect lines that are Haskell, we look for the
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```` ```haskell ```` directive and stop at the end of the code fence.
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Simple enough! Annoyingly, Haskell requires that imports be declared at
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the top of the file. This results in literate haskell programs always
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the top of the file. This results in literate Haskell programs always
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starting with a giant block of imports:
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> -- So first we need to get some boilerplate and imports out of the way.
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- `-h`: ignore this for now
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- `<label>`: ignore this for now
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- `<infile>`: the input lhaskell source code
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- `<outfile>`: the output haskell source code
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- `<outfile>`: the output Haskell source code
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Invoke the runes to handle CLI arguments:
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ghc -o typst-unlit typst-unlit.hs
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```
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And now, we can execute our preprocessor on literate haskell files!
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And now, we can execute our preprocessor on literate Haskell files!
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## Serving
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To test our preprocessor, first, write a literate haskell file
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To test our preprocessor, first, write a literate Haskell file
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containing your typst code:
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````
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```
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#!/usr/bin/env bash
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# this does the same thing as typst-unlit.lhs, but depends on `typst` and `jq`
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# this does the same thing as typst-unlit.lhs, but depends on typst and jq
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# this script does clobber the line numbers, so users beware
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typst query "$3" 'raw.where(lang: "haskell-top")' | jq -r '.[].text' > "$4"
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typst query "$3" 'raw.where(lang: "haskell")' | jq -r '.[].text' >> "$4"
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```
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This document mentions the word “Haskell” 60 times.
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[^1]: <https://gitlab.haskell.org/ghc/ghc/-/tree/master/utils/unlit>
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