How to make an instance polymorphic over constraints?

sstewartgallus · July 20, 2020, 8:31pm

Hi

I’m working on a compiler in tagless final style.

How can I make sort of memoizer more polymorphic of constraints?

sstewartgallus/hs-callbypushvalue/blob/master/src/AsMemoized.hs#L49


extract (C x) = Program (Unique.withStream x LabelMap.empty)

data AsMemoized (k :: * -> Constraint)

instance HasCode (AsMemoized k) where
  newtype Code (AsMemoized k) a = C (forall x. Unique.Stream x -> (forall t. k t => LabelMap (Code t) -> Code t a))

instance HasData (AsMemoized k) where
  newtype Data (AsMemoized k) a = D (forall x. Unique.Stream x -> (forall t. k t => LabelMap (Code t) -> Data t a))

instance HasGlobals (AsMemoized SystemF) where
  global g = C $ \_ ->
    let g' = global g
     in \_ -> g'

instance HasConstants (AsMemoized SystemF) where
  constant k = D $ \_ ->
    let k' = constant k
     in \_ -> k'
  unit = D $ \_ ->
    let u = unit

Using ~ doesn’t work