[Haskell] rekursive array problem

[Mirko Rahn]

Andreas Fuertig wrote:

> fillArray ["a"]
> [[("a",True)],[("a",False)]]
> 
> fillArray ["a","b"]
> [[("a",True),("b",True)],[("a",False),("b",True)],[("a",True),("b",False)],
> [("a",False),("b",False)]]

A simple solution is:

fill :: [a] -> [[(a,Bool)]]
fill [] = [[]]
fill (x:xs) = do v <- [True,False] ; vs <- fill xs ; return ((x,v):vs)

have fun,

-- 
-- Mirko Rahn -- Tel +49-721 608 7504 --
--- http://liinwww.ira.uka.de/~rahn/ ---