Re: writing a function to build a list of ints from user input

6 May 2003

      On Tue, May 06, 2003 at 08:14:46AM -0500, Galen Menzel wrote:
...
On Tue, May 06, 2003 at 07:22:20AM -0400, David Roundy wrote:
...
On Tue, May 06, 2003 at 05:02:56AM -0500, Galen Menzel wrote:
...
makeList :: IO [Int]
makeList = do s <- getLine
        case read s of
      0 -> return []
      x -> do xs <- makeList
      	return (x:xs)
I changed the if to a case so that (read s) doesn't get called twice.
Does the compiler not optimize away identical calls? Or is it not allowed
to, for some reason?
This is certainly possible, particularly with a referentially
transparent language.  There's a technique called memoization that
...
Hmm... Looks like I was confusing memoization with common-
subexpression elimination.

Sorry!
galen