Splitting list into a list of possible tuples

Question

I need to split a list into a list of all possible tuples, but I\'m unsure of how to do so.

For example:

pairs [\"cat\",\"dog\",\"mouse\"]
         


        

Answer 1

My approach, which is somewhat similar to others'. It doesn't require Eq.

allpairs :: [t] -> [(t,t)]
allpairs [] = []
allpairs [_] = []
allpairs (x:xs) = concatMap (\y -> [(x,y),(y,x)]) xs ++ allpairs xs