Trait Function

pub trait Function<A, B, O> {
    // Required method
    fn with(self, prefix: A) -> impl Fn(B);
}

A trait extension for binary functions (Fn(A, B) -> O).

It enables you to use a bunch of nifty functional programming paradigms that work well with iced.

Required Methods

fn with(self, prefix: A) -> impl Fn(B)

Applies the given first argument to a binary function and returns a new function that takes the other argument.

This lets you partially “apply” a function—equivalent to currying, but it only works with binary functions. If you want to apply an arbitrary number of arguments, create a little struct for them.

When is this useful?

Sometimes you will want to identify the source or target of some message in your user interface. This can be achieved through normal means by defining a closure and moving the identifier inside:

let id = 123;

element.map(move |result| Message::ButtonPressed(id, result))

That’s quite a mouthful. with lets you write:

let id = 123;

element.map(Message::ButtonPressed.with(id))

Effectively creating the same closure that partially applies the id to the message—but much more concise!

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors

impl<F, A, B, O> Function<A, B, O> for F

where F: Fn(A, B) -> O, A: Clone,