traits.md

Traits

^Syntax
Trait :
   trait IDENTIFIER {
      TraitMethod^*
   }

TraitMethod :
   fn IDENTIFIER
      ( FunctionParameters^? )
      FunctionReturnType^? ;\

A trait is a collection of function signatures that a type can implement. Traits are implemented for specific types through separate implementations. A type can implement a trait by providing a function body for each of the trait's functions. Traits can be used as type bounds for generic functions to restrict the types that can be used with the function.

All traits define an implicit type parameter Self that refers to "the type that is implementing this interface".

Example of the Min trait from Fe's standard library:

pub trait Min {
  fn min() -> Self;
}

Example of the i8 type implementing the Min trait:

impl Min for i8 {
  fn min() -> Self {
    return -128
  }
}

Example of a function restricting a generic parameter to types implementing the Compute trait:

pub trait Compute {
  fn compute(self) -> u256;
}

struct Example {
  fn do_something<T: Compute>(val: T) -> u256 {
    return val.compute()
  }
}