<A>(): Combiner<A>Creates a Combiner that always returns the first (left) argument.
When to use
Use when you want "first write wins" semantics while merging values.
Details
combine(self, that) returns self and ignores that.
Example (Keeping the first value)
import { Combiner } from "effect"
const First = Combiner.first<number>()
console.log(First.combine(1, 2))
// Output: 1export function function first<A>(): Combiner<A>Creates a Combiner that always returns the first (left) argument.
When to use
Use when you want "first write wins" semantics while merging values.
Details
combine(self, that) returns self and ignores that.
Example (Keeping the first value)
import { Combiner } from "effect"
const First = Combiner.first<number>()
console.log(First.combine(1, 2))
// Output: 1
first<function (type parameter) A in first<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 first<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((self: Aself, _: A_) => self: Aself)
}