<A, B>(self: Option<A>, that: Option<B>): Option<[A, B]>Combines two Options into a Some containing a tuple [A, B] if both
are Some.
When to use
Use when you need to require two Option values to both be Some and keep
both values as a tuple.
Details
- Both
Some→Some([a, b]) - Either
None→None
Example (Pairing two Options)
import { Option } from "effect"
console.log(Option.product(Option.some("hello"), Option.some(42)))
// Output: { _id: 'Option', _tag: 'Some', value: ['hello', 42] }
console.log(Option.product(Option.none(), Option.some(42)))
// Output: { _id: 'Option', _tag: 'None' }export const const product: <A, B>(
self: Option<A>,
that: Option<B>
) => Option<[A, B]>
Combines two Options into a Some containing a tuple [A, B] if both
are Some.
When to use
Use when you need to require two Option values to both be Some and keep
both values as a tuple.
Details
- Both
Some → Some([a, b])
- Either
None → None
Example (Pairing two Options)
import { Option } from "effect"
console.log(Option.product(Option.some("hello"), Option.some(42)))
// Output: { _id: 'Option', _tag: 'Some', value: ['hello', 42] }
console.log(Option.product(Option.none(), Option.some(42)))
// Output: { _id: 'Option', _tag: 'None' }
product = <function (type parameter) A in <A, B>(self: Option<A>, that: Option<B>): Option<[A, B]>A, function (type parameter) B in <A, B>(self: Option<A>, that: Option<B>): Option<[A, B]>B>(self: Option<A>self: type Option<A> = None<A> | Some<A>The Option data type represents optional values. An Option<A> is either
Some<A>, containing a value of type A, or None, representing absence.
When to use
Use to represent initial values that may not yet exist
- Returning from partial functions (not defined for all inputs)
- Managing optional fields in data structures
Namespace containing utility types for Option.
When to use
Use to access type-level helpers associated with Option.
Option<function (type parameter) A in <A, B>(self: Option<A>, that: Option<B>): Option<[A, B]>A>, that: Option<B>that: type Option<A> = None<A> | Some<A>The Option data type represents optional values. An Option<A> is either
Some<A>, containing a value of type A, or None, representing absence.
When to use
Use to represent initial values that may not yet exist
- Returning from partial functions (not defined for all inputs)
- Managing optional fields in data structures
Namespace containing utility types for Option.
When to use
Use to access type-level helpers associated with Option.
Option<function (type parameter) B in <A, B>(self: Option<A>, that: Option<B>): Option<[A, B]>B>): type Option<A> = None<A> | Some<A>The Option data type represents optional values. An Option<A> is either
Some<A>, containing a value of type A, or None, representing absence.
When to use
Use to represent initial values that may not yet exist
- Returning from partial functions (not defined for all inputs)
- Managing optional fields in data structures
Namespace containing utility types for Option.
When to use
Use to access type-level helpers associated with Option.
Option<[function (type parameter) A in <A, B>(self: Option<A>, that: Option<B>): Option<[A, B]>A, function (type parameter) B in <A, B>(self: Option<A>, that: Option<B>): Option<[A, B]>B]> =>
const isSome: <A>(
self: Option<A>
) => self is Some<A>
Checks whether an Option contains a value (Some).
When to use
Use when you need to branch on a present Option before accessing .value.
Details
- Acts as a type guard, narrowing to
Some<A>
Example (Checking for Some)
import { Option } from "effect"
console.log(Option.isSome(Option.some(1)))
// Output: true
console.log(Option.isSome(Option.none()))
// Output: false
isSome(self: Option<A>self) && const isSome: <A>(
self: Option<A>
) => self is Some<A>
Checks whether an Option contains a value (Some).
When to use
Use when you need to branch on a present Option before accessing .value.
Details
- Acts as a type guard, narrowing to
Some<A>
Example (Checking for Some)
import { Option } from "effect"
console.log(Option.isSome(Option.some(1)))
// Output: true
console.log(Option.isSome(Option.none()))
// Output: false
isSome(that: Option<B>that) ? const some: <A>(value: A) => Option<A>Wraps the given value into an Option to represent its presence.
When to use
Use to wrap a known present value as Option
- Returning a successful result from a partial function
Details
- Always returns
Some<A>
- Does not filter
null or undefined; use
fromNullishOr
for that
Example (Wrapping a value)
import { Option } from "effect"
// ┌─── Option<number>
// ▼
const value = Option.some(1)
console.log(value)
// Output: { _id: 'Option', _tag: 'Some', value: 1 }
some([self: Option<A>(parameter) self: {
_tag: "Some";
_op: "Some";
value: A;
valueOrUndefined: A;
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; <…;
toString: () => string;
toJSON: () => unknown;
}
Some<A>.value: Avalue, that: Option<B>(parameter) that: {
_tag: "Some";
_op: "Some";
value: A;
valueOrUndefined: A;
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; <…;
toString: () => string;
toJSON: () => unknown;
}
Some<B>.value: Bvalue]) : const none: <A = never>() => Option<A>Creates an Option representing the absence of a value.
When to use
Use to represent a missing or uninitialized value, such as returning "no
result" from a function.
Details
- Returns
Option<never>, which is a subtype of Option<A> for any A
- Always returns the same singleton instance
Example (Creating an empty Option)
import { Option } from "effect"
// ┌─── Option<never>
// ▼
const noValue = Option.none()
console.log(noValue)
// Output: { _id: 'Option', _tag: 'None' }
none()