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Pair

structure Pair[T, U] {
    first: T
    second: U
}

An ordered pair of two values, possibly of different types.

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first​

Pair.first: Pair[T, U] -> T

The first element of the pair.

fst​

let fst: Pair[T, U] -> T = pair_first

The first projection.

map​

define map[V, W](self, f: T -> V, g: U -> W) -> Pair[V, W] {
    pair_map(f, g, self)
}

Applies functions to both components.

map_first​

define map_first[V](self, f: T -> V) -> Pair[V, U] {
    pair_map_first(f, self)
}

Applies a function to the first component.

map_second​

define map_second[V](self, f: U -> V) -> Pair[T, V] {
    pair_map_second(f, self)
}

Applies a function to the second component.

second​

Pair.second: Pair[T, U] -> U

The second element of the pair.

snd​

let snd: Pair[T, U] -> U = pair_second

The second projection.

swap​

define swap(self) -> Pair[U, T] {
    Pair.new(self.second, self.first)
}

Swaps the first and second elements of the pair.