Effect (v3)

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JSONSchema

JSONSchema: Missing jsonSchema annotation

This error occurs when attempting to generate a JSON Schema for a type that has no direct representation in JSON Schema, such as bigint.

To resolve this, add a jsonSchema annotation to specify how the type should be represented.

For refined schemas, ensure that each refinement includes a jsonSchema annotation that describes its constraints.

For more details, see Customizing JSON Schema Generation.

JSONSchema: Missing identifier annotation for recursive schemas

This error occurs when generating a JSON Schema for a recursive or mutually recursive schema that lacks an identifier annotation.

Recursive schemas need a unique identifier annotation to ensure correct references in the generated JSON Schema. Without it, the schema generator cannot resolve the self-referencing structure.

To resolve this, ensure that recursive schemas include an identifier annotation.

For more details, see Recursive and Mutually Recursive Schemas.

JSONSchema: Unsupported Post Rest Elements

This error occurs when generating a JSON Schema for a tuple that includes post-rest elements, elements appearing after a rest parameter. JSON Schema does not support this structure.

Example

1
import { 
import Schema
Schema } from "effect"
2

3
//             Element after a rest parameter ───┐
4
// Rest Parameter ────────────────┐              |
5
//                                ▼              ▼
6
const 
const schema: Schema.TupleType<readonly [], [typeof Schema.Number, typeof Schema.String]>
schema = 
import Schema
Schema.
function Tuple<readonly [], [typeof Schema.Number, typeof Schema.String]>(elements: readonly [], rest_0: typeof Schema.Number, rest_1: typeof Schema.String): Schema.TupleType<readonly [], [typeof Schema.Number, typeof Schema.String]> (+2 overloads)@since ― 3.10.0
Tuple([], 
import Schema
Schema.
class Number
export Number@since ― 3.10.0
Number, 
import Schema
Schema.
class String
export String@since ― 3.10.0
String)

JSONSchema: Unsupported Key

This error occurs when attempting to generate a JSON Schema for a structure that includes unsupported key types, such as symbol. JSON Schema only supports string-based keys.

Example

1
import { 
import Schema
Schema } from "effect"
2

3
// Schema with a symbol key (not allowed in JSON Schema)
4
const 
const schema: Schema.Struct<{
    [x: symbol]: typeof Schema.String;
}>
schema = 
import Schema
Schema.
function Struct<{
    [x: symbol]: typeof Schema.String;
}>(fields: {
    [x: symbol]: typeof Schema.String;
}): Schema.Struct<{
    [x: symbol]: typeof Schema.String;
}> (+1 overload)@since ― 3.10.0
Struct({
5
  [
var Symbol: SymbolConstructor
Symbol.
SymbolConstructor.for(key: string): symbol
Returns a Symbol object from the global symbol registry matching the given key if found.
Otherwise, returns a new symbol with this key.
@param ― key key to search for.
for("my-symbol")]: 
import Schema
Schema.
class String
export String@since ― 3.10.0
String
6
})

as there is no way to represent this in JSON Schema.