PEP 659: Add Go

pep-0695.rst

@@ -914,6 +914,7 @@ Java provides no way to specify a default type argument.
 
         // Generic method
         public <S extends Number> void method1(S value) { }
+
         // Use site variance
         public void method1(ClassA<? super Integer> value) { }
     }
@@ -1123,7 +1124,12 @@ Kotlin provides no way to specify a default type argument.
     class ClassC<in S, out T>
 
     // Generic function
-    fun <T> func1(): T { }
+    fun <T> func1(): T {
+
+        // Use site variance
+        val covariantA: ClassA<out Number>
+        val contravariantA: ClassA<in Number>
+    }
 
     // Generic type alias
     typealias TypeAliasFoo<T> = ClassA<T>
@@ -1179,6 +1185,31 @@ Dart provides no way to specify a default type argument.
     // Generic type alias
     typedef TypeDefFoo<T> = ClassA<T>;
 
+Go
+--
+
+Go uses square brackets to declare type parameters and for specialization.
+The upper bound of a type is specified after the name of the parameter, and
+must always be specified. The keyword ``any`` is used for an unbound type parameter.
+
+Go doesn't support variance; all type parameters are invariant.
+
+Go provides no way to specify a default type argument.
+
+Go does not support generic type aliases.
+
+.. code-block:: go
+
+    // Generic type without a bound
+    type TypeA[T any] struct {
+        t T
+    }
+
+    // Type parameter with upper bound
+    type TypeB[T SomeType1] struct { }
+
+    // Generic function
+    func func1[T any]() { }
 
 
 Summary
@@ -1214,6 +1245,8 @@ Summary
 | Dart       | <>       | extends |        |          | decl      | in, out,  |
 |            |          |         |        |          |           | inout     |
 +------------+----------+---------+--------+----------+-----------+-----------+
+| Go         | []       | T X     |        |          | n/a       | n/a       |
++------------+----------+---------+--------+----------+-----------+-----------+
 | Python     | []       | T: X    |        |          | decl      | inferred  |
 | (proposed) |          |         |        |          |           |           |
 +------------+----------+---------+--------+----------+-----------+-----------+