> Perhaps slightly off-topic. > I have looked at the core-spec document, and had a question regarding the > operational semantics part. > > Given the Core expressions: >> case (let r = 1 : r in r) of (x:xs) -> x > > An interpreter following the semantics would loop on the above expression, as > the S_LetRecReturn rule, the one that throws away let-expressions, never > applies. > >> case (let r = 1 : r in r) of (x:xs) -> x > => S_Case + S_LetRec + S_Var >> case (let r = 1 : r in 1:r) of (x:xs) -> x > => S_Case + S_LetRec + S_Var >> case (let r = 1 : r in 1:1:r) of (x:xs) -> x > etc.
Actually, I don't think it would loop, it would just get stuck: > case (let r = 1 : r in r) of (x:xs) -> x => S_Case + S_LetRec + S_Var > case (let r = 1 : r in 1:r) of (x:xs) -> x => no more rules step apply The body of the let-expression can not be reduced any further since it is a constructor application. I assume it should not get stuck, right? So we would need extra step-reduction rules. -- Christiaan _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://www.haskell.org/mailman/listinfo/ghc-devs
