<T, E>(f: (oe: Option.Option<E>) => SchemaIssue.Issue): Getter<T, E>Creates a getter that always fails with the given issue.
When to use
Use when you need a schema getter that unconditionally rejects input.
- Building custom validation getters that produce specific error types.
Details
- Always fails with the
Issuereturned byf. - The failure function receives the original
Option<E>input for error context.
Example (Defining an always-failing getter)
import { Option, SchemaGetter, SchemaIssue } from "effect"
const rejectAll = SchemaGetter.fail<string, string>(
(oe) => new SchemaIssue.InvalidValue(oe, { message: "not allowed" })
)export function function fail<T, E>(
f: (oe: Option.Option<E>) => SchemaIssue.Issue
): Getter<T, E>
Creates a getter that always fails with the given issue.
When to use
Use when you need a schema getter that unconditionally rejects input.
- Building custom validation getters that produce specific error types.
Details
- Always fails with the
Issue returned by f.
- The failure function receives the original
Option<E> input for error context.
Example (Defining an always-failing getter)
import { Option, SchemaGetter, SchemaIssue } from "effect"
const rejectAll = SchemaGetter.fail<string, string>(
(oe) => new SchemaIssue.InvalidValue(oe, { message: "not allowed" })
)
fail<function (type parameter) T in fail<T, E>(f: (oe: Option.Option<E>) => SchemaIssue.Issue): Getter<T, E>T, function (type parameter) E in fail<T, E>(f: (oe: Option.Option<E>) => SchemaIssue.Issue): Getter<T, E>E>(f: (
oe: Option.Option<E>
) => SchemaIssue.Issue
oe: Option.Option<E>oe: import OptionOption.type Option.Option = /*unresolved*/ anyOption<function (type parameter) E in fail<T, E>(f: (oe: Option.Option<E>) => SchemaIssue.Issue): Getter<T, E>E>) => import SchemaIssueSchemaIssue.type Issue =
| SchemaIssue.Leaf
| SchemaIssue.Filter
| SchemaIssue.Encoding
| SchemaIssue.Pointer
| SchemaIssue.Composite
| SchemaIssue.AnyOf
The root discriminated union of all validation error nodes.
When to use
Use when typing the error channel in Effect<A, Issue, R> results from
schema parsing, or when writing custom formatters or issue-tree walkers.
Details
Every node has a _tag field for pattern-matching. The union includes both
terminal
Leaf
types and composite types that wrap inner issues:
Filter
,
Encoding
,
Pointer
,
Composite
,
AnyOf
. All Issue instances have a toString() that delegates to
the default formatter, so String(issue) produces a human-readable message.
Issue): 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 fail<T, E>(f: (oe: Option.Option<E>) => SchemaIssue.Issue): Getter<T, E>T, function (type parameter) E in fail<T, E>(f: (oe: Option.Option<E>) => SchemaIssue.Issue): Getter<T, E>E> {
return new constructor Getter<T, E, never>(run: (input: Option.Option<E>, options: SchemaAST.ParseOptions) => Effect.Effect<Option.Option<T>, SchemaIssue.Issue, never>): Getter<T, E, never>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((oe: Option.Option<E>oe) => import EffectEffect.fail(f: (
oe: Option.Option<E>
) => SchemaIssue.Issue
oe: Option.Option<E>oe)))
}