2009/3/12 7stud
7stud
writes: Why does
take (0 - 1) [1, 2, 3]
produce a result but not
take -1 [1, 2, 3]
? Thanks
Well, immediately after I hit the submit button, I thought I'd try this:
*Main> take (-1) [1, 2, 3] []
So why are the parentheses needed there?
I think because take -1 [1,2,3] is parsed as (take - 1 ) [1,2,3] or something like that. If you look to the error message, and translate the haskellese in plain english, it says so. "In the second argument of `(-)', namely `1 [1, 2, 3]' " : so it looks like is looking for the two arguments of infix operator (-), the first being 'take'. But I don't understand because it says that 1 [1,2,3] is a single argument... "In the definition of `it': it = take - 1 [1, 2, 3]" notice the blank between the minus sign and 1: even if you write -1, it understands - 1. So, ghc is trying to be helpful here :-) Ciao ----- FB