Hi, Am Mittwoch, den 24.07.2013, 01:41 -0700 schrieb Michael Sloan:
Another non-answer is to take a look at using vaccum[0] and vaccum-graphviz[1] together, to get an idea of the heap structure of unforced values. I've made a gist demonstrating how to use these to visualize the heap without forcing values[2]. This doesn't show any concrete values (as that would require some serious voodoo), but does show how the heap changes due to thunks being forced.
if you want to stay in GHCi with it you can use ghc-heapview instead of vacuum: Prelude> :script /home/jojo/.cabal/share/ghc-heap-view-0.5.1/ghci Prelude> let x = [1..] Prelude> take 20 x [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20] Prelude> :printHeap x Prelude> :printHeap x let x1 = S# 20 in S# 1 : S# 2 : S# 3 : S# 4 : S# 5 : S# 6 : S# 7 : S# 8 : S# 9 : S# 10 : S# 11 : S# 12 : S# 13 : S# 14 : S# 15 : S# 16 : S# 17 : S# 18 : S# 19 : x1 : _thunk x1 (S# 1) For this kind of infinite values you don’t see its finite, but for others you do: Prelude> let inf = let x = "ha" ++ x in x Prelude> take 20 inf "hahahahahahahahahaha" Prelude> :printHeap inf let x1 = C# 'h' : C# 'a' : x1 in x1 Greetings, Joachim -- Joachim “nomeata” Breitner mail@joachim-breitner.de • http://www.joachim-breitner.de/ Jabber: nomeata@joachim-breitner.de • GPG-Key: 0x4743206C Debian Developer: nomeata@debian.org