Polyglot CheatSheet - Higher Order Functions

Last Updated: 2022-04-03

Higher order function: a function that either takes a function as parameter, or returns a function after its execution.

First-class functions are the functions that are treated as values. It means, those functions can be assigned to a variable and can be passed around as an argument.

C++

Since C++11, we can use std::function as an argument or the returned result.

Java

Before Java 8, use anonymous inner classes; after Java 8, we can pass the function as an argument:

Collections.sort(list, (String a, String b) -> {
    return a.compareTo(b);
});

Python

Use decorators:

@foo
def bar():
    pass

It's equivelent to:

def bar():
    pass
# Pass bar() to foo() as an argument
bar = foo(bar)