(u: unknown): u is Transformation<any, any, unknown, unknown>Returns true if u is a Transformation instance.
When to use
Use to check whether a value is already a schema transformation before wrapping it.
Details
- Pure predicate, no side effects.
- Acts as a TypeScript type guard.
Example (Checking a value)
import { SchemaTransformation } from "effect"
SchemaTransformation.isTransformation(SchemaTransformation.trim())
// true
SchemaTransformation.isTransformation({ decode: null, encode: null })
// falseexport function function isTransformation(
u: unknown
): u is Transformation<any, any, unknown, unknown>
Returns true if u is a Transformation instance.
When to use
Use to check whether a value is already a schema transformation before
wrapping it.
Details
- Pure predicate, no side effects.
- Acts as a TypeScript type guard.
Example (Checking a value)
import { SchemaTransformation } from "effect"
SchemaTransformation.isTransformation(SchemaTransformation.trim())
// true
SchemaTransformation.isTransformation({ decode: null, encode: null })
// false
isTransformation(u: unknownu: unknown): u: unknownu is class Transformation<in out T, in out E, RD = never, RE = never>class Transformation {
_tag: 'Transformation';
decode: SchemaGetter.Getter<T, E, RD>;
encode: SchemaGetter.Getter<E, T, RE>;
flip: () => Transformation<E, T, RE, RD>;
compose: <T2, RD2, RE2>(other: Transformation<T2, T, RD2, RE2>) => Transformation<T2, E, RD | RD2, RE | RE2>;
}
Represents a bidirectional transformation between a decoded type T and an encoded
type E, built from a pair of Getters.
When to use
Use when you need a schema transformation that defines how a schema converts
between two representations.
- You want to compose multiple transformations into a pipeline.
- You want to flip a transformation to swap decode/encode.
Details
This is the primary building block for Schema.decodeTo, Schema.encodeTo,
Schema.decode, Schema.encode, and Schema.link. Each direction is a
SchemaGetter.Getter that handles optionality, failure, and Effect services.
- Immutable —
flip() and compose() return new instances.
flip() swaps the decode and encode getters.compose(other) chains: this.decode then other.decode for decoding,
other.encode then this.encode for encoding.
Example (Composing two transformations)
import { SchemaTransformation } from "effect"
const trimAndLower = SchemaTransformation.trim().compose(
SchemaTransformation.toLowerCase()
)
// decode: trim then lowercase
// encode: passthrough (both directions)
Transformation<any, any, unknown, unknown> {
return import PredicatePredicate.hasProperty(u: unknownu, const TypeId: "~effect/SchemaTransformation/Transformation"TypeId)
}