Fix replace if different for index lambda

[kaushikcfd]

Provided test fails on main.

[inducer]

Thx!

[majosm]

I'm too slow, but:

https://github.com/inducer/pymbolic/blob/ae07a0f041094de88e1d7d89162e03171d2520e7/pymbolic/primitives.py#L895-L897

    def __iter__(self) -> NoReturn:
        # prevent infinite loops (e.g. when inserting into numpy arrays)
        raise TypeError("expression types are not iterable")

It looks like ExpressionNode is only Iterable because this method exists... is there a way to fix that?

[majosm]

Never mind, I see inducer/pymbolic#10.

[kaushikcfd]

Never mind, I see inducer/pymbolic#10.

Thanks for the references.