jhc

Download

jhc@haskell.org

April 2015

4 participants
2 discussions

Is there a working example of type families usage?
by Artyom 21 Apr '15

21 Apr '15

I tried this: |{-# LANGUAGE TypeFamilies #-} class C xwhere type A x | It fails with this error: |Temp/jhc1.hs:4 - Error: parse error at "}" | Standalone type families don’t work either: |{-# LANGUAGE TypeFamilies #-} type family A x | |Temp/jhc1.hs:3 - Error: parse error at "family" | Is there an example somewhere that I missed while googling?

2 1

A possible bug with constraints being perceived as multiparameter type classes
by Artyom 21 Apr '15

21 Apr '15

This (empty) instance declaration |instance Num (a,b) =>Num (a,b,Int) where | produces the following error when compiled with jhc 0.8.2: |$ Temp/jhc-0.8.2/jhc Temp/jhc1.hs jhc Temp/jhc1.hs jhc 0.8.2 (mydniquipepo-32) Finding Dependencies... Using Ho Cache: '/home/yom/.jhc/cache' Temp/jhc1.hs:1 - Error: Invalid Class. multiparameter classes not yet supported: (Num,[HsTyTuple [HsTyVar {hsTypeName = a},HsTyVar {hsTypeName = b}]]) | Am I misunderstanding something, or is it a legitimate bug?

3 3