<S extends object, E extends EntryEvolver<S>>(e: E): (
self: S
) => EntryEvolved<S, E>
<S extends object, E extends EntryEvolver<S>>(
self: S,
e: E
): EntryEvolved<S, E>Transforms both keys and values of a struct selectively. Each per-key
function receives (key, value) and must return a [newKey, newValue]
tuple. Keys without a corresponding function are copied unchanged.
When to use
Use when you need to rename a key and change its value in one step.
Details
The return type is fully tracked at the type level.
Example (Transforming keys and values together)
import { pipe, Struct } from "effect"
const result = pipe(
{ amount: 100, label: "total" },
Struct.evolveEntries({
amount: (k, v) => [`${k}Cents`, v * 100],
label: (k, v) => [k, v.toUpperCase()]
})
)
console.log(result) // { amountCents: 10000, label: "TOTAL" }export const const evolveEntries: {
<S extends object, E extends EntryEvolver<S>>(
e: E
): (self: S) => EntryEvolved<S, E>
<S extends object, E extends EntryEvolver<S>>(
self: S,
e: E
): EntryEvolved<S, E>
}
Transforms both keys and values of a struct selectively. Each per-key
function receives (key, value) and must return a [newKey, newValue]
tuple. Keys without a corresponding function are copied unchanged.
When to use
Use when you need to rename a key and change its value in one step.
Details
The return type is fully tracked at the type level.
Example (Transforming keys and values together)
import { pipe, Struct } from "effect"
const result = pipe(
{ amount: 100, label: "total" },
Struct.evolveEntries({
amount: (k, v) => [`${k}Cents`, v * 100],
label: (k, v) => [k, v.toUpperCase()]
})
)
console.log(result) // { amountCents: 10000, label: "TOTAL" }
evolveEntries: {
<function (type parameter) S in <S extends object, E extends EntryEvolver<S>>(e: E): (self: S) => EntryEvolved<S, E>S extends object, function (type parameter) E in <S extends object, E extends EntryEvolver<S>>(e: E): (self: S) => EntryEvolved<S, E>E extends type EntryEvolver<S> = {
readonly [K in keyof S]?:
| ((k: K, v: S[K]) => [PropertyKey, unknown])
| undefined
}
function (type parameter) S in <S extends object, E extends EntryEvolver<S>>(e: E): (self: S) => EntryEvolved<S, E>S>>(e: E extends EntryEvolver<S>e: function (type parameter) E in <S extends object, E extends EntryEvolver<S>>(e: E): (self: S) => EntryEvolved<S, E>E): (self: S extends objectself: function (type parameter) S in <S extends object, E extends EntryEvolver<S>>(e: E): (self: S) => EntryEvolved<S, E>S) => type EntryEvolved<S, E> = {
[K in keyof S as K extends keyof E
? E[K] extends (
k: K,
v: S[K]
) => [
infer NK extends PropertyKey,
infer _V
]
? NK
: K
: K]: K extends keyof E
? E[K] extends (
k: K,
v: S[K]
) => [infer _NK, infer V]
? V
: S[K]
: S[K]
}
function (type parameter) S in <S extends object, E extends EntryEvolver<S>>(e: E): (self: S) => EntryEvolved<S, E>S, function (type parameter) E in <S extends object, E extends EntryEvolver<S>>(e: E): (self: S) => EntryEvolved<S, E>E>
<function (type parameter) S in <S extends object, E extends EntryEvolver<S>>(self: S, e: E): EntryEvolved<S, E>S extends object, function (type parameter) E in <S extends object, E extends EntryEvolver<S>>(self: S, e: E): EntryEvolved<S, E>E extends type EntryEvolver<S> = {
readonly [K in keyof S]?:
| ((k: K, v: S[K]) => [PropertyKey, unknown])
| undefined
}
function (type parameter) S in <S extends object, E extends EntryEvolver<S>>(self: S, e: E): EntryEvolved<S, E>S>>(self: S extends objectself: function (type parameter) S in <S extends object, E extends EntryEvolver<S>>(self: S, e: E): EntryEvolved<S, E>S, e: E extends EntryEvolver<S>e: function (type parameter) E in <S extends object, E extends EntryEvolver<S>>(self: S, e: E): EntryEvolved<S, E>E): type EntryEvolved<S, E> = {
[K in keyof S as K extends keyof E
? E[K] extends (
k: K,
v: S[K]
) => [
infer NK extends PropertyKey,
infer _V
]
? NK
: K
: K]: K extends keyof E
? E[K] extends (
k: K,
v: S[K]
) => [infer _NK, infer V]
? V
: S[K]
: S[K]
}
function (type parameter) S in <S extends object, E extends EntryEvolver<S>>(self: S, e: E): EntryEvolved<S, E>S, function (type parameter) E in <S extends object, E extends EntryEvolver<S>>(self: S, e: E): EntryEvolved<S, E>E>
} = dual<(...args: Array<any>) => any, <S extends object, E extends EntryEvolver<S>>(self: S, e: E) => EntryEvolved<S, E>>(arity: 2, body: <S extends object, E extends EntryEvolver<S>>(self: S, e: E) => EntryEvolved<S, E>): ((...args: Array<any>) => any) & (<S extends object, E extends EntryEvolver<S>>(self: S, e: E) => EntryEvolved<S, E>) (+1 overload)Creates a function that can be called in data-first style or data-last
(pipe-friendly) style.
When to use
Use to expose one implementation through both direct and pipe-friendly
call styles.
Details
Pass either the arity of the uncurried function or a predicate that decides
whether the current call is data-first. Arity is the common case. Use a
predicate when optional arguments make arity ambiguous.
Example (Selecting data-first or data-last style by arity)
import { Function, pipe } from "effect"
const sum = Function.dual<
(that: number) => (self: number) => number,
(self: number, that: number) => number
>(2, (self, that) => self + that)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
Example (Defining overloads with call signatures)
import { Function, pipe } from "effect"
const sum: {
(that: number): (self: number) => number
(self: number, that: number): number
} = Function.dual(2, (self: number, that: number): number => self + that)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
Example (Selecting data-first or data-last style with a predicate)
import { Function, pipe } from "effect"
const sum = Function.dual<
(that: number) => (self: number) => number,
(self: number, that: number) => number
>(
(args) => args.length === 2,
(self, that) => self + that
)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
dual(
2,
<function (type parameter) S in <S extends object, E extends EntryEvolver<S>>(self: S, e: E): EntryEvolved<S, E>S extends object, function (type parameter) E in <S extends object, E extends EntryEvolver<S>>(self: S, e: E): EntryEvolved<S, E>E extends type EntryEvolver<S> = {
readonly [K in keyof S]?:
| ((k: K, v: S[K]) => [PropertyKey, unknown])
| undefined
}
function (type parameter) S in <S extends object, E extends EntryEvolver<S>>(self: S, e: E): EntryEvolved<S, E>S>>(self: S extends objectself: function (type parameter) S in <S extends object, E extends EntryEvolver<S>>(self: S, e: E): EntryEvolved<S, E>S, e: E extends EntryEvolver<S>e: function (type parameter) E in <S extends object, E extends EntryEvolver<S>>(self: S, e: E): EntryEvolved<S, E>E): type EntryEvolved<S, E> = {
[K in keyof S as K extends keyof E
? E[K] extends (
k: K,
v: S[K]
) => [
infer NK extends PropertyKey,
infer _V
]
? NK
: K
: K]: K extends keyof E
? E[K] extends (
k: K,
v: S[K]
) => [infer _NK, infer V]
? V
: S[K]
: S[K]
}
function (type parameter) S in <S extends object, E extends EntryEvolver<S>>(self: S, e: E): EntryEvolved<S, E>S, function (type parameter) E in <S extends object, E extends EntryEvolver<S>>(self: S, e: E): EntryEvolved<S, E>E> => {
return function buildStruct<S, (k: keyof S, v: S[keyof S]) => any>(source: S, f: (k: keyof S, v: S[keyof S]) => any): anyWalk source; for each key decide what to emit via the small callback.
The callback returns either
• undefined → nothing is copied, or
• [newKey, newVal]
so every public API just supplies a different callback.
buildStruct(self: S extends objectself, (k: keyof Sk, v: S[keyof S]v) => (var Object: ObjectConstructorProvides functionality common to all JavaScript objects.
Object.ObjectConstructor.hasOwn(o: object, v: PropertyKey): booleanDetermines whether an object has a property with the specified name.
hasOwn(e: E extends EntryEvolver<S>e, k: string | number | symbolk) ? (e: E extends EntryEvolver<S>e as any)[k: keyof Sk](k: string | number | symbolk, v: S[keyof S]v) : [k: string | number | symbolk, v: S[keyof S]v]))
}
)