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Install Cabal, GHC, or GHCJS with one Nix command
# install nix (5.5 mins)
curl https://nixos.org/nix/install | sh
# open a new shell to source nix
bash
# query available haskell compilers
nix-env -qaP -A nixpkgs.haskell.compiler [QUERY]
# install ghc (2.5 mins, cached binary)
nix-env -iA nixpkgs.haskell.compiler.ghc865
# ghc is now in your PATH
ghc --version
# query cabal install version
nix-env -qaP -A nixpkgs.haskellPackages.cabal-install
# install cabal install (0.5 mins, cached binary)
nix-env -iA nixpkgs.haskellPackages.cabal-install
# cabal is now in your PATH
cabal --version
# Install ghcjs (take one sleep, build from source, with `-j1`)
# https://github.com/NixOS/nixpkgs/blob/67e07308236bb7a9fa11f3b599838384db650ecb/pkgs/development/compilers/ghcjs-ng/default.nix#L96
# It will appear to hang at places like 'Preprocessing library for unix-2.7.2.2..'
# Use `ps -ef | grep nix` to check it is still doing work.
nix-env -iA nixpkgs.haskell.compiler.ghcjs
# ghcjc is now in your PATH
ghcjs --version
# cleanup disk space from unused nix stuff
nix-collect-garbage -d
# uninstall everything
sudo rm -rf /nix
@louispan
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More nix commands, only if you want to use nix to install packages for reproducible releases.
Otherwise, just use cabal to build packages

query haskell packages

nix-env -qaP -A nixpkgs.haskellPackages [QUERY]

list pre-built packages for a specific compiler

nix-env -qaP -A nixpkgs.haskell.packages.ghc865 [QUERY]

The first segment of a package can be replaced with -f NAMESPACE

nix-env -qaP -A nixpkgs.haskell.packages.ghc865 [QUERY]
nix-env -f "<nixpkgs>" -qaP -A haskell.packages.ghc865 [QUERY]

@louispan
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louispan commented Oct 11, 2019

To build ghcjs faster, you can git clone git@github.com:NixOS/nixpkgs.git, remove the -j1, (the -j1 flag is used to prevent an intermittent panic which might have been fixed) and then install the modified pkg

nix-env -f /path/to/cloned/nixpkgs -iA haskell.compiler.ghcjs

@MurakamiKennzo
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Thanks, I did it.😘

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