Trait std::slice::Concat

source ·
pub trait Concat<Item>
where Item: ?Sized,
{ type Output; // Required method fn concat(slice: &Self) -> Self::Output; }
🔬This is a nightly-only experimental API. (slice_concat_trait #27747)
Expand description

Helper trait for [T]::concat.

Note: the Item type parameter is not used in this trait, but it allows impls to be more generic. Without it, we get this error:

error[E0207]: the type parameter `T` is not constrained by the impl trait, self type, or predica
   --> library/alloc/src/
608 | impl<T: Clone, V: Borrow<[T]>> Concat for [V] {
    |      ^ unconstrained type parameter

This is because there could exist V types with multiple Borrow<[_]> impls, such that multiple T types would apply:

pub struct Foo(Vec<u32>, Vec<String>);

impl std::borrow::Borrow<[u32]> for Foo {
    fn borrow(&self) -> &[u32] { &self.0 }

impl std::borrow::Borrow<[String]> for Foo {
    fn borrow(&self) -> &[String] { &self.1 }

Required Associated Types§


type Output

🔬This is a nightly-only experimental API. (slice_concat_trait #27747)

The resulting type after concatenation

Required Methods§


fn concat(slice: &Self) -> Self::Output

🔬This is a nightly-only experimental API. (slice_concat_trait #27747)

Implementation of [T]::concat

Object Safety§

This trait is not object safe.



impl<S> Concat<str> for [S]
where S: Borrow<str>,

Note: str in Concat<str> is not meaningful here. This type parameter of the trait only exists to enable another impl.


impl<T, V> Concat<T> for [V]
where T: Clone, V: Borrow<[T]>,


type Output = Vec<T>