Agreed. I like "select" better too, and the regular vs "Asc" version
is a nice parallel with fromList and fromAscList.
Chad
On 8/10/07, Tillmann Rendel
Non-negative is obvious for a list of indexes. Ordered makes sense implementation-wise, and should be easy to match for many applications. But is it a sensible constraint on a standard library function?
For Data.List, I would prefer a multi-pass select function like this:
select :: Integral n => [n] -> [a] -> [a] select ns xs = select' 0 ns xs where select' k [] _ = [] select' k (n:ns) [] = select' k ns [] select' k nns@(n:ns) yys@(y:ys) = case k `compare` n of LT -> select' (succ k) nns ys EQ -> y : select' k ns yys GT -> select nns xs
*Main> select [0, 2, 2, 1] "abcde" "accb"
There could be selectAsc for the special case of ordered indexes, to avoid keeping the whole input list in memory.
Tillmann