A Type that pairs a value with a tag.

The tag is ignored at runtime as evidenced by the only value constructor:

Tagged : value -> Tagged tag value

An alias for the Tagged value constructor.

Explicitly changes the tag of a value.

Forces you to recognize that the value is being interpreted differently from before.

We can remove the tag when we're done making additional compile-time assertions.

Useful for applying a function on a Tagged value.

foo =
    map String.toUpper aTaggedString

Useful for building more useful functions:

map f =
    ap (Tagged f)


map2 f x =
    ap (map f x)


map3 f x y =
    ap (map2 f x y)

An alternative to ap:

foo =
    map2 Array.get index arr

Useful for composing functions together in a pipeline:

foo =
    Tagged Array.set
        |> andMap index
        |> andMap value
        |> andMap arr

Useful for restricting the tag created in a polymorphic function.

Useful for restricting the tag created in a polymorphic function.

Useful when you have a function that throws away a tag prematurely, but you still need the tag later.