I must admit I'm stumped! I don't see any significant difference between those two programs. On Thu, Nov 08, 2018 at 11:04:34AM -0500, Tyson Whitehead wrote:
Constant memory code (RES 6MB):
{-# LANGUAGE ViewPatterns #-}
module Main (main) where
import Data.Either
(length -> lx,length -> ly) = partitionEithers (repeat $ Left ())
main = do print lx print ly
Unbounded memory:
module Main (main) where
import Data.Either
(xs, ys) = partitionEithers (repeat $ Left ())
main = do print $ length xs print $ length ys
Cheers! -Tyson
PS: The constant-memory view-pattern version seems to compile down to
lxly = case partitionEithers (repeat $ Left ()) of (xs,ys) -> (length xs,length ys)
main = do print (case lxly of (lx,_) -> lx) print (case lxly of (_,ly) -> ly)
while the unbounded-memory non-view-pattern one compiles down to
xsys = partitionEithers (repeat $ Left ()) xs = case xsys of (xs,_) -> xs ys = case xsys of (_,ys) -> ys
main = do print (length xs) print (length ys)