#🔒 Pyright: Weird typing with union set operator with dicts

17 messages · Page 1 of 1 (latest)

sly elk
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type Foo = Literal["foo"]

bar1: dict[Foo, int] = {'foo': 1}
bar2: dict[Foo, int] = {k: v for k, v in bar1.items()}

baz3: dict[Foo, int] = bar1 | bar2
baz4: dict[Foo, int] = bar1 | {k: v for k, v in bar1.items()}  # error

Pyright: Type "dict[str, int]" is not assignable to declared type "dict[Foo, int]"
  "dict[str, int]" is not assignable to "dict[Foo, int]"
    Type parameter "_KT@dict" is invariant, but "str" is not the same as "Foo
image.png
turbid brookBOT
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@sly elk

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sly elk
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@steady hamlet
@spark swan
Idk if you two wanted to look at it, but it seems to be some silly pyright issue

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i presume there's not much I can do about this, other than just make an in-between variable

steady hamlet
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What's the inferred type of baz2?

sly elk
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if I remove the type annotation for bar2, I get the same error for baz3 as well. Let me renumber the variables for clarity

# 
type Foo = Literal["foo"]

bar1: dict[Foo, int] = {'foo': 1}
bar2 = {k: v for k, v in bar1.items()}  # note the missing type annotation here in this new code block

baz1: dict[Foo, int] = bar1 | bar2  # error x
baz2: dict[Foo, int] = bar1 | {k: v for k, v in bar1.items()}  # also error x (mentioned in OP)
image.png
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the inferred type is correct

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Then when I add type annotations, it types it correctly, and no type warnings/errors for invalid type casting stuff

image.png
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it might be a bit unclear with this many images. I can write it out as code block if that helps

spark swan
steady hamlet
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Yeah, seems like pyright is unable to stick to the type with a dict comp

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Perhaps there is already an issue open on their GitHub

turbid brookBOT
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