Lambdas are accepted by the type checker but not actually checked

[JukkaL]

You can use lambdas in code, but the type checker basically ignores them and always gives them the 'any' type.

Code like this is accepted, which is obviously wrong:

int x = lambda y: 'x'

[JukkaL]

Implemented bidirectional type inference for lambdas. It works correctly in common cases but it still fails if you give sufficiently tricky code.