Haskell: Multiple Case Statements in Single Function

Question

I want to include more than one case statement in a Haskell function (see below for an example of a hypothetical function).

However, it is not legal Haskell. What is a b

Answer 1

In general, it looks like what you want is guards. However, as already mentioned, your function is not a single expression. Assuming that you want to return a tuple of strings, it can be written like this using guards (and some added fun from Arrows):

import Control.Arrow

testx x | x < 0      = "Less then zero."
        | otherwise  = "Greater then or equal to zero."

testy y | y == "foo" = "The name is foo."
        | otherwise  = "The name is not foo."

tester = curry (testx *** testy)

You could also drop the Control.Arrow bit all together and write:

tester x y = (testx x, testy y)