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Understand Typedef

This video was last updated on Jun 21 2022

Learn how to define an alias to functions to make your them easier to both use & read.


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In the last episode, we passed a function to a function and in doing so, we created a function signature that was a little complex and unwieldy. Dart allows to use an alias when referring to functions and other types. In such a way, it allows to create a shorthand alias so instead of using a clunky method signature, you use the alias instead. You can typedef used throughout the Flutter codebase.

int multiply(int a, int b) {
    return a * b;
int processScores(List<int> scores, int Function(int, int) processor) {
    var total = 0;
    for (var score in scores) {
        total += processor(score, 2);
    return total;
void main() {
  var scores = [54, 75, 32];
  print(processScores(scores, multiply));
typedef ScoreModifier
typedef ScoreModifier = int Function(int, int);
int processScores(List<int> scores, ScoreModifier processor) {