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PEP 747: Clarify that TypeForm(T) is always a TypeForm[T] #4736

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JelleZijlstra merged 1 commit into from
Dec 8, 2025
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PEP 747: Clarify that TypeForm(T) is always a TypeForm[T] #4736

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4 changes: 3 additions & 1 deletion peps/pep-0747.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -289,11 +289,13 @@ Type checkers should validate that this argument is a valid type expression::
x1 = TypeForm(str | None)
reveal_type(v1) # Revealed type is "TypeForm[str | None]"

x2 = TypeForm("list[int]")
x2 = TypeForm('list[int]')
revealed_type(v2) # Revealed type is "TypeForm[list[int]]"

x3 = TypeForm('type(1)') # Error: invalid type expression

The static type of a ``TypeForm(T)`` is ``TypeForm[T]``.

At runtime the ``TypeForm(...)`` callable simply returns the value passed to it.

This explicit syntax serves two purposes. First, it documents the developer's
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