Edit Question - KnowledgeHub

Title Body

I type this code into the interpreter and memory is rapidly consumed: last [1..10^7] `seq` () I can't see why this needs more than O(1) space. If i do just (which should be the same, because Show forces weak head normal form, so seq is redundant?): last [1..10^7] ...it works fine. I'm unable to reproduce this situation outside the interpreter. What's going on here? Here are some test cases: http://hpaste.org/69234 Things to note: By running in the interpreter, I load wtf.hs without compiling it, and type wtf<n> in ghci. By compiling, I do ghc --make wtf.hs && ./wtf . last can be substituted for a sum with strict accumulator or a function that finds the max element in the list, and the space leak still happens I haven't seen this behaviour when using $! instead of seq . I tried adding a dummy () parameter because I thought maybe this is a CAF problem. Changes nothing. It's probably not a problem with functions on Enum , because I can reproduce the behaviour with wtf5 and later, which don't use Enum at all. It's probably not a problem with Num , Int , or Integer , because I can reproduce the behaviour without them in wtf14 and wtf16 . I tried reproducing the problem with Peano arithmetic to take lists and integers out of the equation (fetching the at the end of of 10^9), but ran into other sharing/space leak problems I don't understand when trying to implement * .

Tags (comma-separated) Cancel