added Haskell's foldl

svn path=/nixpkgs/trunk/; revision=13553
2008-12-02 12:28:21 +00:00 · 2008-12-02 12:28:21 +00:00 · 9e7846d214
commit 9e7846d214
parent 0b49861c7b
1 changed files with 6 additions and 0 deletions
--- a/pkgs/lib/default.nix
+++ b/pkgs/lib/default.nix
@ -96,6 +96,12 @@ rec {
    then nul
    else op (head list) (fold op nul (tail list));

+  # Haskell's fold
+  foldl = op: nul: list:
+    if list == []
+    then nul
+    else fold op (op nul (head list)) (tail list);
+
    
  # Concatenate a list of lists.
  concatList = x : y : x ++ y;