PEP 647 TypeGuard
E884133
PEP 647 TypeGuard is a Python typing feature that allows developers to define user-defined type guard functions, enabling more precise type narrowing and improved static type checking.
All labels observed (1)
| Label | Occurrences |
|---|---|
| PEP 647 TypeGuard canonical | 1 |
How this entity was disambiguated
This entity first appeared as the object of triple T10763916 — resolving that mention is where its identity was fixed. The disambiguator weighed these candidate entities and picked the highlighted one (or “None”, minting a new entity). This is how homonymy is resolved: the same surface form can point to different entities.
NED1
Entity disambiguation (via context triple)
gpt-5-mini-2025-08-07
Target entity: PEP 647 TypeGuard Context triple: [Python 3.10, hasTypingFeature, PEP 647 TypeGuard]
-
A.
PEP 484
PEP 484 is the Python Enhancement Proposal that introduced a standard for type hints in Python, forming the basis of the language’s static typing ecosystem.
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B.
PEP 585
PEP 585 is a Python Enhancement Proposal that introduced built-in generic types (like list[int] and dict[str, int]) as a modern replacement for many typing module aliases.
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C.
PEP 695
PEP 695 is a Python Enhancement Proposal that introduces a new, more concise syntax for type parameter declarations to improve the language’s support for generics and static typing.
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D.
PEP 636
PEP 636 is a Python Enhancement Proposal that serves as a tutorial-style guide to the structural pattern matching feature introduced in Python 3.10.
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E.
PEP 634
PEP 634 is the Python Enhancement Proposal that formally specifies the semantics of structural pattern matching introduced in Python 3.10.
- F. None of above. chosen
- G. Unsure - the case is ambiguous/there is not enough information to decide.
NED2
Entity disambiguation (via description)
gpt-5-mini-2025-08-07
Target entity: PEP 647 TypeGuard Target entity description: PEP 647 TypeGuard is a Python typing feature that allows developers to define user-defined type guard functions, enabling more precise type narrowing and improved static type checking.
-
A.
PEP 484
PEP 484 is the Python Enhancement Proposal that introduced a standard for type hints in Python, forming the basis of the language’s static typing ecosystem.
-
B.
PEP 585
PEP 585 is a Python Enhancement Proposal that introduced built-in generic types (like list[int] and dict[str, int]) as a modern replacement for many typing module aliases.
-
C.
PEP 695
PEP 695 is a Python Enhancement Proposal that introduces a new, more concise syntax for type parameter declarations to improve the language’s support for generics and static typing.
-
D.
PEP 636
PEP 636 is a Python Enhancement Proposal that serves as a tutorial-style guide to the structural pattern matching feature introduced in Python 3.10.
-
E.
PEP 634
PEP 634 is the Python Enhancement Proposal that formally specifies the semantics of structural pattern matching introduced in Python 3.10.
- F. None of above. chosen
Statements (47)
| Predicate | Object |
|---|---|
| instanceOf |
PEP
ⓘ
Python typing feature ⓘ |
| affects | type checkers behavior ⓘ |
| backportedFor | Python versions earlier than 3.10 ⓘ |
| backportLocation | typing_extensions.TypeGuard ⓘ |
| belongsTo |
Python type system
ⓘ
Python typing module NERFINISHED ⓘ |
| category | Typing PEP NERFINISHED ⓘ |
| clarifies | how user-defined predicates influence type narrowing ⓘ |
| defines | typing.TypeGuard NERFINISHED ⓘ |
| definesConcept | TypeGuard NERFINISHED ⓘ |
| definesSyntaxElement | TypeGuard[X] return annotation ⓘ |
| designDecision |
TypeGuard is covariant in its type parameter
NERFINISHED
ⓘ
TypeGuard is intended only for return types, not parameters NERFINISHED ⓘ |
| documentationLocation | https://peps.python.org/pep-0647/ ⓘ |
| exampleUse | def is_str_list(val: list[object]) -> TypeGuard[list[str]] ⓘ |
| hasAuthor | Eric Traut NERFINISHED ⓘ |
| hasName | PEP 647: User-Defined Type Guards NERFINISHED ⓘ |
| introducedIn | Python 3.10 NERFINISHED ⓘ |
| language | Python NERFINISHED ⓘ |
| moduleLocation | typing.TypeGuard NERFINISHED ⓘ |
| motivatedBy |
limitations of isinstance-based narrowing
ⓘ
need for reusable predicate functions ⓘ |
| primaryGoal |
enable user-defined type guards
ⓘ
improve static type checking precision ⓘ support more precise type narrowing ⓘ |
| relatedTo |
PEP 484
NERFINISHED
ⓘ
PEP 544 NERFINISHED ⓘ PEP 589 NERFINISHED ⓘ |
| replacesPattern | ad-hoc isinstance checks for complex predicates ⓘ |
| requires | TypeGuard generic parameter to be a subtype of input type ⓘ |
| returnTypeConstraint | TypeGuard must be used as function return type ⓘ |
| runtimeEffect | no direct runtime enforcement ⓘ |
| scope | static type checking only ⓘ |
| semantics |
if function returns True, argument type is narrowed to TypeGuard parameter
ⓘ
type narrowing applies only in True branch ⓘ type narrowing is local to the guarded expression ⓘ |
| status | Accepted ⓘ |
| targetVersion | Python 3.10 NERFINISHED ⓘ |
| usedBy |
Pylance
NERFINISHED
ⓘ
Pyre NERFINISHED ⓘ Pyright NERFINISHED ⓘ mypy NERFINISHED ⓘ static type checkers ⓘ |
| usedFor |
flow-sensitive type analysis
ⓘ
refining union types ⓘ type narrowing ⓘ |
How these facts were elicited
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Instruction
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Input
Subject: PEP 647 TypeGuard Description of subject: PEP 647 TypeGuard is a Python typing feature that allows developers to define user-defined type guard functions, enabling more precise type narrowing and improved static type checking.
Referenced by (1)
Full triples — surface form annotated when it differs from this entity's canonical label.