yup, i have that!

    wrapFetch prefetchValue0# (error "this shouldn't get evaluated")

in the test suite! 

in contrast 

    wrapFetch prefetchValue0# $! (error "this shouldn't get evaluated") does explode

shall I add a "should fail" test with the latter? (it doesn't seem worthwhile)

On Sun, Nov 23, 2014 at 3:53 PM, Edward Kmett <ekmett@gmail.com> wrote:

Maybe test for laziness in the argument by just putting something in that goes boom when forced, e.g. 'undefined'?

On Sun, Nov 23, 2014 at 2:04 PM, Carter Schonwald <carter.schonwald@gmail.com> wrote:

Hey All,

as part of trying to get some fixups for how prefetch works into 7.10,

i'm adding a "prefetchValue" primop that prefetchs the memory location of a lifted heap value 

namely 

several operations of the following form

primop PrefetchValueOp1 "prefetchValue1#" GenPrimOp

   a -> State# s -> State# s

   with strictness  = { \ _arity -> mkClosedStrictSig [botDmd, topDmd] topRes }

I'd like some feedback on the strictness information design by someone who's familiar with how that piece of GHC. the idea being that prefetchValue is lazy in its polymorphic argument (it doesn't force it, it just does a prefetch on the heap location, which may or may not be evaluated).

https://phabricator.haskell.org/D350

is the code in question. And i *believe* i'm testing for being lazy in that argument correctly.

thoughts?

many thanks!

-Carter

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