GHC *is* resource hungry

[Simon Marlow]

As far as I know, Hugs doesn't hash-cons types, yet it manages to
typecheck these pathalogical examples in reasonable time/space.  I
vaguely recall there being a specific modification to Hugs's typechecker
to handle this, but I can't remember what it was.

Cheers,
	Simon

> -----Original Message-----
> From: glasgow-haskell-bugs-admin at haskell.org 
> [mailto:glasgow-haskell-bugs-admin at haskell.org] On Behalf Of 
> Simon Peyton-Jones
> Sent: 28 May 2003 15:57
> To: Ralf Hinze
> Cc: GHC bugs
> Subject: RE: GHC *is* resource hungry
> 
> I bet it's massive types.  Translate the program into system 
> F and see.
> (I remember this came up when looking at Okasaki's sequences of code
> combinators.)
> 
> GHC doesn't try to hash-cons types, because it usually doesn't matter,
> but I bet it does here.
> 
> S
> 
> | -----Original Message-----
> | From: glasgow-haskell-bugs-admin at haskell.org
> [mailto:glasgow-haskell-bugs-admin at haskell.org] On
> | Behalf Of Ralf Hinze
> | Sent: 28 May 2003 15:32
> | To: glasgow-haskell-bugs at haskell.org
> | Subject: GHC *is* resource hungry
> | 
> | Here is a harmless little program (no recursion, no data types)
> | which GHC doesn't manage to compile (well, the kernel kills GHC
> | after a while on a machine with generous 512MB of main memory
> | and 1GB of swap space).
> | 
> | > begin next = next id
> | > leaf k i next = next (k i)
> | > fork k next = next (\ t u -> k (t + u))
> | > end x = x
> | > main = print (begin fork fork fork fork fork fork fork fork fork
> fork leaf 0 leaf 0 leaf 0 leaf 0 leaf 0
> | leaf 0 leaf 0 leaf 0 leaf 0 leaf 0 leaf 0 end)
> | 
> | Both Hugs and nhc98 accept it almost immediately.
> | 
> | Cheers, Ralf
> | 
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