refinement-types

Various hacks are documented in stitch with comments marked with XXX.
Some of them are no longer necessary and can be removed, others are still needed and could be improved by having them link a relevant issue or by describing the error they avoid in some more detail.

This issue is to make a pass over the stitch-lh code to update them. Fixing them in the LH repo would suffice for now (stitch-l

String interpolation is the last feature from the old C++ compiler that is still unimplemented in the rust compiler.

Once implemented this feature should desugar strings in the form of "... ${expr} ..." into "... " ++ cast expr : string ++ " ...". This looks like the following in the Ast:

FunctionCall(Variable("++"), vec![
    StringLiteral("... "),
    FunctionCall(Variable("++")