Forward references

[bartvm]

Python allows for forward references.

def f():
    return g()  # g has not been defined yet during parsing

def g():
    return 1

This is not a problem as long as the parser is called after the definition of g. To support forward references in general (e.g. in an @myia decorator) we have to postpone name resolution until after the entire scope has been parsed.

For local forward references we have to actually separate the name resolution from the parsing i.e. h should remain unresolved while parsing g under the assumption that it is a forward declaration (and then be resolved to h when we come across it). Note that this is related to #11 i.e. if we perform name resolution statically we need to ensure that there is only one name declaration corresponding to the forward reference (otherwise we need to do it dynamically by introducing environments).

def f():
    def g():
        return h()
    def h():
        return g()