Why is this program leaking memory ?

[Ahn Ki-yung]

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I'm playing with the lazy abstract machine of 1997 Sestoft's paper.
I implemented this with haskell using ghc 5.04.3.

I lambda lifted the original input expression to prevent
memory leak of "Lazy Abstarc Machine", and it works fine.
I tested with the leaky program example of the Sestoft 97 paper.

[kyagrd@OBIWAN transform]$ cat test.txt
let ff = \n.let i=\x.x in ff i
in ff ff

I printed the 4 tuples (Heap, Exp, Env, Stack) each step.
It goes on and on like this.

[kyagrd@OBIWAN transform]$ ./main.exe < test.txt
let "ff"=\"n".let "i"=\"x"."x" in "ff" "i" in "ff" "ff"
let 1=\2.let 3=\4.4 in 1 3 in 1 1
let -1=\2.-1 -3 -3=\4.4 in -1 -1
let -1=\2.-1 -3 -3=\4.4 in -1 -1
let 0=\0.1 2 0=\0.0 in 0 0
([],let 0=\0.1 2 0=\0.0 in 0 0,[],[])
([(2,(\0.1 2,[2,1])),(1,(\0.0,[2,1]))],0 0,[2,1],[])
([(2,(\0.1 2,[2,1])),(1,(\0.0,[2,1]))],0,[2,1],[2])
([(2,(\0.1 2,[2,1])),(1,(\0.0,[2,1]))],\0.1 2,[2,1],[2])
([(2,(\0.1 2,[2,1])),(1,(\0.0,[2,1]))],1 2,[2,2,1],[])
([(2,(\0.1 2,[2,1])),(1,(\0.0,[2,1]))],1,[2,2,1],[1])
([(2,(\0.1 2,[2,1])),(1,(\0.0,[2,1]))],\0.1 2,[2,1],[1])
([(2,(\0.1 2,[2,1])),(1,(\0.0,[2,1]))],1 2,[1,2,1],[])
([(2,(\0.1 2,[2,1])),(1,(\0.0,[2,1]))],1,[1,2,1],[1])
([(2,(\0.1 2,[2,1])),(1,(\0.0,[2,1]))],\0.1 2,[2,1],[1])
([(2,(\0.1 2,[2,1])),(1,(\0.0,[2,1]))],1 2,[1,2,1],[])
([(2,(\0.1 2,[2,1])),(1,(\0.0,[2,1]))],1,[1,2,1],[1])
([(2,(\0.1 2,[2,1])),(1,(\0.0,[2,1]))],\0.1 2,[2,1],[1])
([(2,(\0.1 2,[2,1])),(1,(\0.0,[2,1]))],1 2,[1,2,1],[])
...


But Strangely the Haskell heap memory leaks if I omit printing
every step but only print the result.

[kyagrd@OBIWAN transform]$ ./main.exe < test.txt
let "ff"=\"n".let "i"=\"x"."x" in "ff" "i" in "ff" "ff"
let 1=\2.let 3=\4.4 in 1 3 in 1 1
let -1=\2.-1 -3 -3=\4.4 in -1 -1
let -1=\2.-1 -3 -3=\4.4 in -1 -1
let 0=\0.1 2 0=\0.0 in 0 0
c:\MyDoc\iFolder\kyagrd\LAZY\transform\main.exe: fatal error:
RTS exhausted max heap size (268435456 bytes)


I attach my source code except for the parser and lexer stuff.
I switched between two main' and main fucntion.

Why, in the Main module, "printNreduce" do not leak but
while "printeval" leaks ? Can't understand this behavior.


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