This enables us to stop treating the return type as a Pattern (which is really isn't), treat return types more consistently with other static types in the typechecker, and drop ReturnTypeContext.
Additional changes:
- Merge TypeCheckFunDef with TypeOfFunDef.
- Handle implicit conversions in `return` statements.
- Require function type literals to have an explicit `->`.
- Move consistency check for omitted returns from TypeChecker to ResolveControlFlow.
This was born out of wanting FunctionDeclaration to explicitly have a Block for a body, and became a bit more of specifying types around. Note this forces exec_program to generate a Block for print()'s body, which is probably more correct as now we can expect a standard FunctionDeclaration AST structure, even for the built-ins.
There is a syntactic change here: a continuation's body is now a Block, not just a Statement. I've added an example disallowed test case. I think this is more reasonable syntax.
Other than that, note that optional_else now generates a valid Block. This has me thinking about whether we can eliminate Sequence, but that seemed well out of scope for this.
Geoff Romer
Jon Meow