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Merge pull request #4553 from mausch/patch-1

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Fix Haskell example
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Eelco Dolstra 2021-02-17 10:18:42 +01:00 committed by GitHub
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15
doc/manual/src/command-ref/nix-shell.md
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@ -232,22 +232,23 @@ terraform apply
> in a nix-shell shebang.
Finally, using the merging of multiple nix-shell shebangs the following
Haskell script uses a specific branch of Nixpkgs/NixOS (the 18.03 stable
Haskell script uses a specific branch of Nixpkgs/NixOS (the 20.03 stable
branch):
```haskell
#! /usr/bin/env nix-shell
#! nix-shell -i runghc -p "haskellPackages.ghcWithPackages (ps: [ps.HTTP ps.tagsoup])"
#! nix-shell -I nixpkgs=https://github.com/NixOS/nixpkgs/archive/nixos-18.03.tar.gz
#! nix-shell -i runghc -p "haskellPackages.ghcWithPackages (ps: [ps.download-curl ps.tagsoup])"
#! nix-shell -I nixpkgs=https://github.com/NixOS/nixpkgs/archive/nixos-20.03.tar.gz
import Network.HTTP
import Network.Curl.Download
import Text.HTML.TagSoup
import Data.Either
import Data.ByteString.Char8 (unpack)
-- Fetch nixos.org and print all hrefs.
main = do
resp <- Network.HTTP.simpleHTTP (getRequest "http://nixos.org/")
body <- getResponseBody resp
let tags = filter (isTagOpenName "a") $ parseTags body
resp <- openURI "https://nixos.org/"
let tags = filter (isTagOpenName "a") $ parseTags $ unpack $ fromRight undefined resp
let tags' = map (fromAttrib "href") tags
mapM_ putStrLn $ filter (/= "") tags'
```