<A>(a: A): Combiner<A>Creates a Combiner that ignores both arguments and always returns the
given constant value.
When to use
Use when you need a combiner that always returns a fixed value, including when a generic API requires a combiner but the result is predetermined.
Details
combine(self, that) returns the constant a and ignores both arguments.
Example (Always returning zero)
import { Combiner } from "effect"
const Zero = Combiner.constant(0)
console.log(Zero.combine(42, 99))
// Output: 0export function function constant<A>(a: A): Combiner<A>Creates a Combiner that ignores both arguments and always returns the
given constant value.
When to use
Use when you need a combiner that always returns a fixed value, including
when a generic API requires a combiner but the result is predetermined.
Details
combine(self, that) returns the constant a and ignores both arguments.
Example (Always returning zero)
import { Combiner } from "effect"
const Zero = Combiner.constant(0)
console.log(Zero.combine(42, 99))
// Output: 0
constant<function (type parameter) A in constant<A>(a: A): Combiner<A>A>(a: Aa: function (type parameter) A in constant<A>(a: A): Combiner<A>A): interface Combiner<A>Represents a strategy for combining two values of the same type A. A
Combiner contains a single combine method that takes two values and
returns a merged result. It does not include an identity/empty value; use
Reducer when you need one.
When to use
Use when you need to describe how two values of the same type
merge, pass a reusable combining strategy to library functions like
Struct.makeCombiner or Option.makeCombinerFailFast, or define the
combining step for a Reducer.
Example (Combining numbers with addition)
import { Combiner } from "effect"
const Sum = Combiner.make<number>((self, that) => self + that)
console.log(Sum.combine(3, 4))
// Output: 7
Combiner<function (type parameter) A in constant<A>(a: A): Combiner<A>A> {
return function make<A>(
combine: (self: A, that: A) => A
): Combiner<A>
Creates a Combiner from a binary function.
When to use
Use when you have a custom combining operation that is not covered by
the built-in constructors (min, max, first, last, constant).
Details
The returned combiner's combine method delegates to the provided function.
Any purity, associativity, or mutation behavior comes from that function.
Example (Multiplying numbers)
import { Combiner } from "effect"
const Product = Combiner.make<number>((self, that) => self * that)
console.log(Product.combine(3, 5))
// Output: 15
make(() => a: Aa)
}