Improving Predicate Usability of Schema.is

[gcanti]

Before this update, the Schema.is(mySchema) function couldn't be easily used as a predicate or refinement in common array methods like filter or find. This was because the function's signature was:

(value: unknown, overrideOptions?: AST.ParseOptions) => value is A

Meanwhile, the function expected by methods like filter has the following signature:

(value: unknown, index: number) => value is A

To make Schema.is compatible with these array methods, we've adjusted the function's signature to accept number as a possible value for the second parameter, in which case it is ignored:

-(value: unknown, overrideOptions?: AST.ParseOptions) => value is A
+(value: unknown, overrideOptions?: AST.ParseOptions | number) => value is A

Here's a practical example comparing the behavior before and after the change:

Before:

import { Schema } from "@effect/schema"

declare const array: Array<string | number>

/*
Throws an error:
No overload matches this call.
...
Types of parameters 'overrideOptions' and 'index' are incompatible.
*/
const strings = array.filter(Schema.is(Schema.String))

Now:

import { Schema } from "@effect/schema"

declare const array: Array<string | number>

// const strings: string[]
const strings = array.filter(Schema.is(Schema.String))

Note that the result has been correctly narrowed to string[].

[changeset-bot]

🦋 Changeset detected

Latest commit: 6f23303

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 18 packages

Name	Type
@effect/schema	Patch
@effect/cli	Patch
@effect/experimental	Patch
@effect/platform-browser	Patch
@effect/platform-bun	Patch
@effect/platform-node-shared	Patch
@effect/platform-node	Patch
@effect/platform	Patch
@effect/rpc-http	Patch
@effect/rpc	Patch
@effect/sql	Patch
@effect/sql-mssql	Patch
@effect/sql-mysql2	Patch
@effect/sql-pg	Patch
@effect/sql-sqlite-bun	Patch
@effect/sql-sqlite-node	Patch
@effect/sql-sqlite-react-native	Patch
@effect/sql-sqlite-wasm	Patch

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