Crate amonoid

A crate about monoids.

Crate Features

This crate supports the following feature flags, none of which are enabled by default:

• num-traits: Adds a dependency on num_traits to implement Zero for ops::Additive and One for ops::Multiplicative.
• syn: Adds a dependency on syn to implement Monoid for Option<syn::Error>.
• graph-track-inconsistency: Adds edge-case inconsistency detection to hom::graph::Graph (see Graph::input_mut), at the cost of possibly increasing its size.

A note about equality

Some sections in the documentation use equality to state rules that must hold. Strictly speaking, this would of course require the types in question to impl Eq. However, since these requirements aren’t enforced anyway, it is up to the library consumer’s discretion to ensure these on a “best effort” basis. For example, you might want to consider f32 and f64 as monoids under addition or multiplication, even tho they are very much non-associative in general, since they are approximately associative for “tame” inputs (not too large and not too small).

Modules

from_ops

Monoids constructed from existing operations.

hom

Monoid homomorphisms

list

The list monoid.

ops

Operational types that allow the use of the monoid operation as an operator.

Macros

impl_all_monoid_hom

A helper macro that implements all lower tiers of Hom* for you, so you don’t have to repeat yourself so much when implementing HomMut, Hom, or HomStatic.

Structs

Opposite

The opposite monoid (wiki), where combine(a, b) = M::combine(b, a).

Traits

Monoid

A monoid.

MonoidBorrowed

The Borrowed version of a Monoid.

PreMonoidBorrowed

A Borrow of a Monoid.