Trait enso_prelude::PhantomConversions[−][src]

pub trait PhantomConversions: Sized {
    fn phantom_into<P>() -> P
    where
        Self: PhantomInto<P>,
    { ... }

    fn phantom_from<P: PhantomInto<Self>>() -> Self { ... }
}
Expand description

A utility for easy driving of type-level computations from value level. Often we’ve got some type level relations, like a few singleton types, and for each such type we’ve got an associated value. For example, we can define types Int and Float and associate with them WebGlContext::Int and WebGlContext::Float constants encoded as GlEnum. In order to convert Int or Float to the GlEnum we do not need the instance of the types, only the information what type it was. So we can define:

ⓘ
impl From<PhantomData<Int>> for u32 {
    from(_:PhantomData<Int>>) {
        GlEnum(WebGlContext::Int)
    }
}

And use it like:

ⓘ
let val = GlEnum::from(PhantomData::<Int>)

Using this utility we can always write the following code instead:

ⓘ
let val = GlEnum::phantom_from::<Int>()

Provided methods

fn phantom_into<P>() -> P where
    Self: PhantomInto<P>, [src]

fn phantom_from<P: PhantomInto<Self>>() -> Self[src]

Implementors