[readme-lhs](https://tonyday567.github.io/readme-lhs/index.html) [](https://travis-ci.org/tonyday567/readme-lhs)
================================================================================================================================================================================
<blockquote cite>
The language in which we express our ideas has a strong influence on our
thought processes. \~ Knuth
</blockquote>
This is an example of mixing literate haskell with markdown, and in
using Readme.Lhs. The file is composed of several elements:
- literate haskell. Bird-tracks are used, as the alternative method is
latex rather than markdown, which doesn’t survive a pandoc round
trip.
- markdown. All non bird-tracked lines are considered to be markdown.
It’s probably incompatible with haddock, but this may well resolve
with adoption of the [literate markdown ghc
proposal](https://gitlab.haskell.org/ghc/ghc/wikis/literate-markdown).
- fenced code blocks with an output class, which are used to insert
computation results. The fenced code blocks look like:
\`\`\`{.output .example} \`\`\`
[ghc options](https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/flags.html#flag-reference)
--------------------------------------------------------------------------------------------------------
``` haskell
{-# OPTIONS_GHC -Wall #-}
```
[pragmas](https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/lang.html)
------------------------------------------------------------------------------------
``` haskell
-- doctest doesn't look at the cabal file, so you need pragmas here
{-# LANGUAGE NoImplicitPrelude #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE FlexibleInstances #-}
```
[libraries](https://www.stackage.org/)
--------------------------------------
- [protolude](https://www.hackage.org/package/protolude)
- [readme-lhs](https://www.hackage.org/package/readme-lhs)
``` haskell
import Protolude
import Readme.Lhs
```
code
----
- [hoogle](https://www.stackage.org/package/hoogle)
``` haskell
main :: IO ()
main = do
let n = 10
let answer = product [1..n::Integer]
_ <- runOutput ("example.lhs", LHS) ("readme.md", GitHubMarkdown) $ do
output "example1" "Simple example of an output"
```
``` output
Simple example of an output
```
``` haskell
output "example2" (show answer)
```
10! is equal to:
``` output
3628800
```
``` haskell
pure ()
```
Output that doesn’t exist is simply cleared.
``` output
```
hsfiles writeup
===============
A literate-programming friendly; tight work-flow stack template.
other/readme-lhs.hsfiles
other/batteries.hsfiles
-----------------------
This is my latest working template, overly influenced by [lexi-lambda’s
opinionated
guide](https://lexi-lambda.github.io/blog/2018/02/10/an-opinionated-guide-to-haskell-in-2018/).
The template includes:
- some minor tweaks to protolude
- lens, foldl, formatting & text as must have libraries
- generic-lens-labels
workflow
--------
stack build --exec "$(stack path --local-install-root)/bin/readme-lhs-example" --file-watch