<T, E extends T>(): Getter<T, E>Returns the identity getter, typed for when the encoded type E is a subtype of T.
When to use
Use when you need a schema getter that passes values through without
{ strict: false } for an encoded type that narrows the decoded type.
Details
- Same singleton as passthrough — no allocation, optimized in composition.
Example (Passing through subtypes)
import { SchemaGetter } from "effect"
// "hello" extends string, so E extends T
const g = SchemaGetter.passthroughSubtype<string, "hello">()export function function passthroughSubtype<
T,
E extends T
>(): Getter<T, E>
Returns the identity getter, typed for when the encoded type E is a subtype of T.
When to use
Use when you need a schema getter that passes values through without
{ strict: false } for an encoded type that narrows the decoded type.
Details
- Same singleton as
passthrough
— no allocation, optimized in composition.
Example (Passing through subtypes)
import { SchemaGetter } from "effect"
// "hello" extends string, so E extends T
const g = SchemaGetter.passthroughSubtype<string, "hello">()
passthroughSubtype<function (type parameter) T in passthroughSubtype<T, E extends T>(): Getter<T, E>T, function (type parameter) E in passthroughSubtype<T, E extends T>(): Getter<T, E>E extends function (type parameter) T in passthroughSubtype<T, E extends T>(): Getter<T, E>T>(): class Getter<out T, in E, R = never>class Getter {
run: (input: Option.Option<E>, options: SchemaAST.ParseOptions) => Effect.Effect<Option.Option<T>, SchemaIssue.Issue, R>;
map: <T2>(f: (t: T) => T2) => Getter<T2, E, R>;
compose: <T2, R2>(other: Getter<T2, T, R2>) => Getter<T2, E, R | R2>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
Represents a composable transformation from an encoded type E to a decoded type T.
When to use
Use when you need a schema getter to build and compose custom transformations
for Schema.decodeTo or Schema.decode.
Details
A getter wraps a function Option<E> -> Effect<Option<T>, Issue, R>. It
receives Option.None when the encoded key is absent, such as a missing
struct field, and returns Option.None to omit the value from the decoded
output. It fails with Issue on invalid input and may require Effect
services via R. .map(f) applies f to the decoded value inside Some
while leaving None unchanged. .compose(other) chains two getters by
feeding the output of this into other; passthrough getters on either side
are optimized away.
Example (Creating and composing getters)
import { SchemaGetter } from "effect"
const parseNumber = SchemaGetter.transform<number, string>((s) => Number(s))
const double = SchemaGetter.transform<number, number>((n) => n * 2)
const composed = parseNumber.compose(double)
// composed: Getter<number, string> — parses then doubles
Getter<function (type parameter) T in passthroughSubtype<T, E extends T>(): Getter<T, E>T, function (type parameter) E in passthroughSubtype<T, E extends T>(): Getter<T, E>E>
export function function passthroughSubtype<
T,
E extends T
>(): Getter<T, E>
Returns the identity getter, typed for when the encoded type E is a subtype of T.
When to use
Use when you need a schema getter that passes values through without
{ strict: false } for an encoded type that narrows the decoded type.
Details
- Same singleton as
passthrough
— no allocation, optimized in composition.
Example (Passing through subtypes)
import { SchemaGetter } from "effect"
// "hello" extends string, so E extends T
const g = SchemaGetter.passthroughSubtype<string, "hello">()
passthroughSubtype<function (type parameter) T in passthroughSubtype<T>(): Getter<T, T>T>(): class Getter<out T, in E, R = never>class Getter {
run: (input: Option.Option<E>, options: SchemaAST.ParseOptions) => Effect.Effect<Option.Option<T>, SchemaIssue.Issue, R>;
map: <T2>(f: (t: T) => T2) => Getter<T2, E, R>;
compose: <T2, R2>(other: Getter<T2, T, R2>) => Getter<T2, E, R | R2>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
Represents a composable transformation from an encoded type E to a decoded type T.
When to use
Use when you need a schema getter to build and compose custom transformations
for Schema.decodeTo or Schema.decode.
Details
A getter wraps a function Option<E> -> Effect<Option<T>, Issue, R>. It
receives Option.None when the encoded key is absent, such as a missing
struct field, and returns Option.None to omit the value from the decoded
output. It fails with Issue on invalid input and may require Effect
services via R. .map(f) applies f to the decoded value inside Some
while leaving None unchanged. .compose(other) chains two getters by
feeding the output of this into other; passthrough getters on either side
are optimized away.
Example (Creating and composing getters)
import { SchemaGetter } from "effect"
const parseNumber = SchemaGetter.transform<number, string>((s) => Number(s))
const double = SchemaGetter.transform<number, number>((n) => n * 2)
const composed = parseNumber.compose(double)
// composed: Getter<number, string> — parses then doubles
Getter<function (type parameter) T in passthroughSubtype<T>(): Getter<T, T>T, function (type parameter) T in passthroughSubtype<T>(): Getter<T, T>T> {
return const passthrough_: Getter<
any,
any,
never
>
const passthrough_: {
run: (input: Option.Option<E>, options: SchemaAST.ParseOptions) => Effect.Effect<Option.Option<T>, SchemaIssue.Issue, R>;
map: (f: (t: any) => T2) => Getter<T2, any, never>;
compose: (other: Getter<T2, any, R2>) => Getter<T2, any, R2>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}