E4027

Unused type parameter.

Erroneous Example

fn id[T](a: Int) -> Int { a }

The example above declares a type parameter T in the identity function id, however T is not used anywhere in the function signature, giving the following error on line 1:

Unused type parameter 'T'

Suggestion

Make sure the type parameter is used in the function signature:

fn id[T](a: T) -> T { a }