On Mon, Jun 8, 2009 at 1:56 PM, Martijn van
Steenbergen
Magnus Therning wrote:
Is there no way to force repeated evaluation of a pure value? (It'd be nice to be able to perform time measurements on pure code so that it's possible to compare Haskell implementations of algorithms to implementations in other languages, without running into confounding factors.)
I'm really curious about this too.
My guess is that the answer is "no" because doing so would (among other things) mean a thunk have to be copied first before it is evaluated, to preserve the unevaluated version. And what guarantee is there that values further down the expression haven't been evaluated already? Efficient lazy evaluation is hard; inefficient lazy evalation is even harder. ;-)
Yes, I guessed as much. I was hoping that there might be some way of tricking GHC into being more inefficient though, something like a rollback in evaluation state. /M -- Magnus Therning (OpenPGP: 0xAB4DFBA4) magnus＠therning．org Jabber: magnus＠therning．org http://therning.org/magnus identi.ca|twitter: magthe