Deriving `push` for function types should be possible, but even with a wrapped data type is broken.

[dorchard]

We would like to be able to do

push @(->)

to get the function (a -> b)[r] -> a [r] -> b [r] but this currently does not parse. When investigating I tried to make a wrapper:

data Fun a b = Fun (a -> b)

but push @ Fun gives:

Granule> :t push @ Fun
grepl: Cannot push derive for type a0 -> a1
CallStack (from HasCallStack):
  error, called at src/Language/Granule/Synthesis/Deriving.hs:243:3 in granule-frontend-0.9.5.0-5UdUxTp5lHb2yDT2r0aV24:Language.Granule.Synthesis.Deriving