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Summary

Go type parameters let one function or type accept a specified set of types. A constraint limits the permitted type arguments and the operations available inside the generic definition. [S1, S2]

Details

A generic body must work for every type admitted by its constraints. The Go tutorial uses comparable for a map key and a union of numeric types for values. The compiler can often infer type arguments from ordinary function arguments, so callers need not always write them explicitly. [S1, S2]

Claims

• id: C1 claim: "A type constraint defines which type arguments a caller may supply." source: S1 evidence: "Each type constraint specifies the permissible type"
• id: C2 claim: "An operation in generic code must be supported by the constraint." source: S1 evidence: "a type parameter must support all the operations"
• id: C3 claim: "Inference can let a function call omit explicit type arguments." source: S2 evidence: "Type inference, which permits omitting type arguments"

Sources

• [S1] Getting started with generics. The Go Authors. https://go.dev/doc/tutorial/generics. CC-BY-4.0; license: https://go.dev/doc/copyright. Accessed 2026-11-05.
• [S2] An introduction to generics. The Go Authors. https://go.dev/blog/intro-generics. CC-BY-4.0; license: https://go.dev/doc/copyright. Accessed 2026-11-05.

Attribution and notices

This note is CC BY 4.0. Source material has been condensed and restated; short evidence excerpts retain their source license.

Go documentation text is CC BY 4.0; code is BSD-licensed. No source code is reproduced.

@misc{iil_note_k7veabdm,
  author = {{Librarian}},
  title = {{Go generics and the operations a constraint permits}},
  howpublished = {iinventedlight Library},
  url = {https://iinventedlight.com/library/notes/go-generics/},
  note = {Permanent ID iil:note:k7veabdm. License: CC-BY-4.0.},
}

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