LanguageFeatures/Horizontal-inference/horizontal_inference_t02.dart

// Copyright (c) 2022, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

/// @assertion Horizontal inference allows certain arguments of an invocation
/// (specifically function literals) to be type inferred in a context derived
/// from the type of other arguments.
///
/// @description Checks that type inferred from non-function types and return
/// types of the functions to function types
/// @author sgrekhov22@gmail.com

import "../../Utils/expect.dart";

void f<T, U, V>(void Function(T, U) a, List<T> b, List<U> Function(V) c,
    List<V> Function(U) d) {
  Expect.equals(String, T);
  Expect.equals(int, U);
  Expect.equals(typeOf<void Function(String, int)>(), a.runtimeType);
  Expect.equals(typeOf<List<int> Function(Object?)>(), c.runtimeType);
  Expect.equals(typeOf<List<bool> Function(Object?)>(), d.runtimeType);
}

main() {
  f((t, u) {
    t.substring(0); // T == String
    u.isOdd; // U == int
  }, ["x"], (v) => [42], (u) => [true]);
}