Potential bug in Generics section of Python book

[turbolent]

There might be a bug in the TypeCheckLgeneric.

AllType is a Type, and its type parameters are strings:

params: list[str]

GenericVar is a Type, referencing a type parameter, a string:

id: str

In the substitute_type function, the keys of the var_map dictionary seem to be type parameters names (strings, str), and the values seem to be types (Type).

However, in match_types function, in the AllType case, the var_map passed to substitute_type seems to construct a dictionary mapping type parameter names (str) to type parameter names (str), not types:

rename = {ap:p for (ap,p) in zip(arg_ps, ps)}
new_arg_ty = self.substitute_type(arg_ty, rename)

Shouldn't the values be wrapped in GenericVar, i.e.

rename = {ap: GenericVar(p) for (ap,p) in zip(arg_ps, ps)}

That is also what is done in the check_type_equal function, in the AllTypes case:

rename = {p2: GenericVar(p1) for (p1,p2) in zip(ps1,ps2)}

Great work and thank you for the fantastic book!