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Template std.functional.bind

Passes the fields of a struct as arguments to a function.

template bind(alias fun) ;

Can be used with a function literal to give temporary names to the fields of a struct or tuple.

Contained Functions

NameDescription
bind

Parameters

NameDescription
fun Callable that the struct's fields will be passed to.

Returns

A function that accepts a single struct as an argument and passes its fields to fun when called.

Example

Giving names to tuple elements 

import std.typecons : tuple;

auto name = tuple("John", "Doe");
string full = name.bind!((first, last) => first ~ " " ~ last);
writeln(full); // "John Doe"

Example

Passing struct fields to a function 

import std.algorithm.comparison : min, max;

struct Pair
{
    int a;
    int b;
}

auto p = Pair(123, 456);
assert(p.bind!min == 123); // min(p.a, p.b)
assert(p.bind!max == 456); // max(p.a, p.b)

Example

In a range pipeline 

import std.algorithm.iteration : map, filter;
import std.algorithm.comparison : equal;
import std.typecons : tuple;

auto ages = [
    tuple("Alice", 35),
    tuple("Bob",   64),
    tuple("Carol", 21),
    tuple("David", 39),
    tuple("Eve",   50)
];

auto overForty = ages
    .filter!(bind!((name, age) => age > 40))
    .map!(bind!((name, age) => name));

assert(overForty.equal(["Bob", "Eve"]));

Authors

Andrei Alexandrescu

License

Boost License 1.0.