E101: Duplicate Named Type Parameter
This error is emitted when a type parameter is defined multiple times in a named type argument list.
When using named type arguments (type parameter names followed by = and a type), each type parameter can only be specified once.
Example
import scala.language.experimental.namedTypeArguments
def example[A, B](a: A, b: B): (A, B) = (a, b)
val result = example[A = Int, A = String](1, "hello")
Error
-- [E101] Syntax Error: example.scala:5:34 -------------------------------------
5 |val result = example[A = Int, A = String](1, "hello")
| ^^^^^^
| Type parameter A was defined multiple times.
Solution
// Use each type parameter name only once
import scala.language.experimental.namedTypeArguments
def example[A, B](a: A, b: B): (A, B) = (a, b)
val result = example[A = Int, B = String](1, "hello")
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