haskell.nix/docs/reference/library.md

Haskell.nix contains a library of functions for creating buildable package sets from their Nix expression descriptions. The library is what you get when importing Haskell.nix. It might be helpful to load the library in the Nix REPL to test things.

Types

Package Set

The result of mkPkgSet. This is an application of the NixOS module system.

{
  options = { ... };
  config = {
    hsPkgs = { ... };
    packages = { ... };
    compiler = {
      version = "X.Y.Z";
      nix-name = "ghcXYZ";
      packages = { ... };
    };
  };
}

Attribute	Type	Description
options	Module options	The combination of all options set through the modules argument passed to mkPkgsSet.
config		The result of evaluating and applying the options with Haskell.nix
.hsPkgs	Attrset of Haskell Packages	Buildable packages, created from packages
.packages	Attrset of Haskell Package descriptions	Configuration for each package in hsPkgs
.compiler	Attrset

Haskell Package description

Options for building a package. (todo: more info)

Component description

Options for building a component. (todo: more info)

Haskell Package

A derivation which has a components attribute. This derivation is actually just for the package Setup.hs script, and isn't very interesting. To actually use the package, look within the components structure.

components = {
  library = COMPONENT;
  exes = { NAME = COMPONENT; };
  tests = { NAME = COMPONENT; };
  benchmarks = { NAME = COMPONENT; };
  all = COMPONENT;
}

Component

Identifier

A package identifier is an attrset pair of name and version.

Extras

Modules

Top-level attributes

mkStackPkgSet

Creates a package set based on the pkgs.nix output of stack-to-nix.

mkStackPkgSet =
    { stack-pkgs, pkg-def-extras ? [], modules ? []}: ...

Argument	Type	Description
stack-pkgs		import ./pkgs.nix — The imported file generated by stack‑to‑nix.
pkg‑def‑extras	List of Extras	For overriding the package set.
modules	List of Modules	For overriding the package set.

Return value: a pkgSet

mkCabalProjectPkgSet

Creates a package set based on the pkgs.nix output of plan-to-nix.

mkCabalProjectPkgSet =
    { plan-pkgs, pkg-def-extras ? [], modules ? []}: ...

Argument	Type	Description
plan-pkgs		import ./pkgs.nix — The imported file generated by plan‑to‑nix.
pkg‑def‑extras	List of Extras	For overriding the package set.
modules	List of Modules	For overriding the package set.

Return value: a pkgSet

mkPkgSet

This is the base function used by both mkStackPkgSet and mkCabalProjectPkgSet.

Return value: a pkgSet

snapshots

This is an attrset of hsPkgs packages from Stackage.

haskellPackages

A hsPkgs package set

nix-tools

A derivation containing the nix-tools command-line tools.

callStackToNix

callCabalProjectToNix

hackage

stackage

fetchExternal

cleanSourceHaskell

haskellLib

Package-set functions

These functions exist within the hsPkgs package set.

shellFor

Create a nix-shell development environment for developing one or more packages.

shellFor =
    { packages, withHoogle ? true, ...}: ...

Argument	Type	Description
packages	Function	Package selection function. It takes a list of Haskell packages and returns a subset of these packages.
withHoogle	Boolean	Whether to build a Hoogle documentation index and provide the hoogle command.
{ ... }	Attrset	All the other arguments are passed to mkDerivation.

Return value: a derivation

ghcWithPackages

ghcWithHoogle