tvl-depot/tests/lang/lib.nix
Eelco Dolstra 7349bd0176 New primitives:
* `sub' to subtract two numbers.
* `stringLength' to get the length of a string.
* `substring' to get a substring of a string.  These should be enough
  to allow most string operations to be expressed.
2007-01-29 14:23:09 +00:00

26 lines
516 B
Nix

with builtins;
rec {
fold = op: nul: list:
if list == []
then nul
else op (head list) (fold op nul (tail list));
concat =
fold (x: y: x + y) "";
flatten = x:
if isList x
then fold (x: y: (flatten x) ++ y) [] x
else [x];
sum = fold (x: y: add x y) 0;
hasSuffix = ext: fileName:
let lenFileName = stringLength fileName;
lenExt = stringLength ext;
in !(lessThan lenFileName lenExt) &&
substring (sub lenFileName lenExt) lenFileName fileName == ext;
}