On Feb 17, 2006, at 3:30 PM, Ashley Yakeley wrote:
Andy Gill wrote:
I'd like to see a way of enforcing return strictness, that is where you have confidence that what a function is returning is fully evaluated. Imagine a function hstrict; hstrict :: a -> a
Is this like deepseq, that strictly evaluates internal structure using seq?
yes. it is.
With hstrict you can write functions in the style. fun f a b c = hstrict $ .... where ... ...
But surely fun can return the unevaluated thunk (hstrict x)? Since hstrict has not yet been called, it can't do its strictifying magic, whatever that is.
No. hstrict will always be called before returning. Evaluation does not return thunks, they get created by lets/where (at the core level), not by function application/evaluation. Andy Gill