Trait FirstElem 

pub trait FirstElem {
    type Out;

    // Required method
    fn first_elem(&self) -> Option<Self::Out>;
}

Get the first element

Required Associated Types

type Out

Required Methods

fn first_elem(&self) -> Option<Self::Out>

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementations on Foreign Types

impl FirstElem for ()

type Out = Infallible

fn first_elem(&self) -> Option<Self::Out>

impl FirstElem for char

type Out = char

fn first_elem(&self) -> Option<Self::Out>

impl FirstElem for f32

type Out = f32

fn first_elem(&self) -> Option<Self::Out>

impl FirstElem for f64

type Out = f64

fn first_elem(&self) -> Option<Self::Out>

impl FirstElem for i8

type Out = i8

fn first_elem(&self) -> Option<Self::Out>

impl FirstElem for i16

type Out = i16

fn first_elem(&self) -> Option<Self::Out>

impl FirstElem for i32

type Out = i32

fn first_elem(&self) -> Option<Self::Out>

impl FirstElem for i64

type Out = i64

fn first_elem(&self) -> Option<Self::Out>

impl FirstElem for i128

type Out = i128

fn first_elem(&self) -> Option<Self::Out>

impl FirstElem for str

type Out = char

fn first_elem(&self) -> Option<Self::Out>

impl FirstElem for u8

type Out = u8

fn first_elem(&self) -> Option<Self::Out>

impl FirstElem for u16

type Out = u16

fn first_elem(&self) -> Option<Self::Out>

impl FirstElem for u32

type Out = u32

fn first_elem(&self) -> Option<Self::Out>

impl FirstElem for u64

type Out = u64

fn first_elem(&self) -> Option<Self::Out>

impl FirstElem for u128

type Out = u128

fn first_elem(&self) -> Option<Self::Out>

impl<T: FirstElem + ?Sized> FirstElem for &T

type Out = <T as FirstElem>::Out

fn first_elem(&self) -> Option<Self::Out>

impl<T: FirstElem + ?Sized> FirstElem for &mut T

type Out = <T as FirstElem>::Out

fn first_elem(&self) -> Option<Self::Out>

impl<T: FirstElem, const N: usize> FirstElem for [T; N]

type Out = <T as FirstElem>::Out

fn first_elem(&self) -> Option<Self::Out>

impl<T: FirstElem> FirstElem for Option<T>

type Out = <T as FirstElem>::Out

fn first_elem(&self) -> Option<Self::Out>

impl<T: FirstElem> FirstElem for [T]

type Out = <T as FirstElem>::Out

fn first_elem(&self) -> Option<Self::Out>

Implementors