On 2006-07-27 at 01:33EDT Paul Hudak wrote:
Thanks for asking about this -- it probably should be in the paper. Dan Doel's answer is closest to the truth:
I imagine the answer is that having the syntax for it looks nicer/is clearer. "if a b c" could be more cryptic than "if a then b else c" for some values of a, b and c.
except that there was also the simple desire to conform to convention here (I don't recall fewer parentheses being a reason for the choice).
In a sense, it explicitly wasn't: I suggested "if _ then _ else _ fi" -- something I was long used to from Algol68 -- but it was rejected on the ground that there wasn't a dangling else problem in Haskell. I probably muttered something about wanting things to be self-bracketing (I've certainly grumbled inwardly since about having to write "(if _ then _ else _)¹" in some Haskell contexts), but since I'm quite slow witted, I expect that the discussion had moved on by then.
In considering the alternative, I remember the function "cond" being proposed instead of "if", in deference to Scheme and to avoid confusion with people's expectations regarding "if".
Did we talk about Dijkstra's "fat bar", or was that a discussion I had elsewhere? Jón [1] which I find ugly, and besides, making all like constructs self-bracketing would have allowed a saner (to my mind) layout rule. -- Jón Fairbairn Jon.Fairbairn at cl.cam.ac.uk