codebje

with builtins; rec {
  cabalProjects = listToAttrs (if pathExists ./cabal.project
                  then projectParse
                  else [ { name = baseNameOf ./.; value = ./.; } ] );
  projectParse = let
    contents = readFile ./cabal.project;
    trimmed = replaceStrings ["packages:" " "] ["" ""] contents;
    packages = filter (x: isString x && x != "") (split "\n" trimmed);
    package = p: substring 0 (stringLength p - 1) p;
    paths = map (p: let p' = package p; in { name = p'; value = toPath (./. + "/${p'}"); } ) packages;

klapaucius

Строгость и нищета списков.

Map и структурная рекурсия.

Применить функцию к каждому элементу списка - это просто:

GHC/Base.lhs

map _ []     = []
map f (x:xs) = f x : map f xs