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MODULE Plus

Plus

type class

interface Plus<F> extends Alt<F> {
  zero: <A>() => HKT<F, A>
}

The Plus type class extends the Alt type class with a value that should be the left and right identity for alt.

It is similar to Monoid, except that it applies to types of kind * -> *, like Array or Option, rather than concrete types like string or number.

Plus instances should satisfy the following laws:

  1. Left identity: A.alt(zero, fa) == fa
  2. Right identity: A.alt(fa, zero) == fa
  3. Annihilation: A.map(zero, fa) == zero