Jedi does not recognise type parameter lists.

[haiksgit]

The Issue

Starting from Python 3.12, functions, classes and type aliases may contain a type parameter list. However, this new syntax is not supported by Jedi. For example:

import jedi

source = '''
def add(a: float, b: float) -> float:
    """Add two numbers."""
    return a + b

def concat[A, B](a: list[A], b: list[B]) -> list[A | B]:
    """Concatenate two lists."""
    return a + b
'''

script = jedi.Script(source)

add = script.infer(2, 7)
concat = script.infer(6, 10)

print(add)     #-> [<Name full_name='__main__.add', description='def add'>]
print(concat)  #-> []

Because of this, language servers that use Jedi (such as jedi-language-server or python-lsp-server) cannot provide hover information for objects with type parameter lists.

Version Information

• Python 3.12.6
• Jedi 0.19.1

[PeterJCLaw]

My guess is that this is a parso issue (looking their reveals davidhalter/parso#221), though Jedi may need subsequent changes to make use of the parameters.

[davidhalter]

@PeterJCLaw is correct. I wanted to change this in parso a while ago, which would have taken maybe an hour, but the problem is that this is absolutely non-trivial in Jedi and even simply ignoring it in Jedi is probably quite a bit of work.