Can I construct a slice of a generic type with different type parameters?

by

No.

Given a parametrized Token type as:

type Token[T any] struct {
    TokenType string
    Literal   T
}

each instantiation with a different type argument produces a different (named) type.

In other words, Token[string] is not assignable to Token[int]. Nor is it assignable to Token[any] as any here is used as a static type to instantiate T.

So when you construct a slice with a specific instance of Token[T any], different instances are simply not assignable to its element type:

tokS := []*Token[string]{tok1, tok2}
// invalid: cannot use tok2 (variable of type *Token[int]) as type *Token[string] in array or slice literal

The only slice that can hold different types, as Token[string] and Token[int] is []interface{} or []any.

since we wouldn’t be able to infer a type for the Slice of tokens. Is this assumption correct?

Almost. More precisely, the slice of Token wouldn’t infer anything because you yourself must construct it with a concrete instantiation of the generic type

Type inference is used to deduce missing type parameters from those already supplied for function arguments. Generic types must be explicitly instantiated, with a concrete type argument for each type parameter.

More Related Contents:

  1. slice member of a struct pointer is not updated [closed]
  2. Are slices passed by value?
  3. Concatenate two slices in Go
  4. Generic Structs with Go
  5. Can I concurrently write different slice elements
  6. What is a concise way to create a 2D slice in Go?
  7. In Go generics, how to use a common method for types in a union constraint?
  8. generic map value
  9. How can I access a struct field with generics (type T has no field or method)?
  10. range over interface{} which stores a slice
  11. How to create generic method in Go? (method must have no type parameters)
  12. How to assign or return generic T that is constrained by union?
  13. Go error: cannot use generic type without instantiation
  14. How to implement generic interfaces?
  15. How do I reverse a slice in go?
  16. How can I instantiate a non-nil pointer of type argument with generic Go?
  17. Go Generics – Unions
  18. How to delete an element from a Slice in Golang
  19. Why can’t I append to a slice that’s the property of a struct in golang?
  20. How to write a generic function that accepts any numerical type?
  21. Difference between any/interface{} as constraint vs. type of argument?
  22. Big O of append in Golang
  23. How to inspect slice header?
  24. Is there a way to map an array of objects in golang?
  25. How to iterate over a union of slices passed in a generic function? (T has no core type)
  26. Why a generic can’t be assigned to another even if their type arguments can?
  27. Slice chunking in Go
  28. Handle maps with same key type but different value type
  29. Collect values in order, each containing a map
  30. time.Since() with months and years

Leave a Comment