David Roundy wrote:
stats elems = foldl add_elem Map.empty elems
add_elem m x = Map.insertWith (+) x 1 m
main = print $ stats $ take 1000000 $ repeat 1
This program has a space leak and runs out of stack space. I'm guessing
that I'm being bit here by an unnatural amount of laziness in
Map.insertWith, but I can't see how to fix this. :( I'm sure it's
something elementary...
try:
stats = foldl' add_elem Map.empty
add_elem m x = myinsertWith (+) x 1 m
myinsertWith f k v m =
case Map.lookup k m of
Nothing -> Map.insert k v m
Just w -> let r = f v w in r `seq` Map.insert k r m
main = print $ stats $ take 1000000 $ repeat 1
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