Generated selector methods don't take into account named parameters of the field

[ppolesiuk]

For records with fields that have named (implicit, regular named) parameters the generated selector methods fails to type-check. For instance

data T = { x : {~n:Int} -> Unit }

fails with the following error.

fatal error: Cannot resolve an implicit parameter ~n
 -> test.fram
 1 |>data T = { x : {~n:Int} -> Unit }

Similarly, when we replace ~n with n. For optional parameters it works, but not as one would expect.

The problem is that the generated method x looks like the following (modulo some non-important type annotations).

method x (T { x }) = x

To solve this problem, the generated method should explicitly generalize named parameters from the filed, and use the to reisntantiate the field. For instance:

method x {~n=_freshIdent42 : Int} (T { x }) = x {~n=_freshIdent42}

The following observations might be useful.

1. Identifiers used to store named parameters should not collide with other variables. For instance data T = { x : {x : Int} -> Unit } cannot generate method x {x : Int} (T { x }) = x { x }.
2. Type annotations are important, and cannot be inferred in general. For instance data T = { x : {n : {X} -> X} -> Unit } cannot generate method x {n} (T { x }) = x { n }, because the type-checker cannot guess polymorphic types.
3. For type parameters, the type-checker should be able to infer missing information, but it would be nice to preserve names of named typed parameters.