<A>(O: Order<A>): Order<Option<A>>Creates an Order for Option<A> from an Order for A.
When to use
Use when you need to sort Some and None values, with None ordered
before present values and present values compared by a supplied ordering
rule.
Details
Noneis considered less than anySome- Two
Somevalues are compared using the providedOrder - Two
Nonevalues are equal (returns0)
Example (Ordering Options)
import { Number as N, Option } from "effect"
const ord = Option.makeOrder(N.Order)
console.log(ord(Option.none(), Option.some(1)))
// Output: -1
console.log(ord(Option.some(1), Option.none()))
// Output: 1
console.log(ord(Option.some(1), Option.some(2)))
// Output: -1export const const makeOrder: <A>(
O: Order<A>
) => Order<Option<A>>
Creates an Order for Option<A> from an Order for A.
When to use
Use when you need to sort Some and None values, with None ordered
before present values and present values compared by a supplied ordering
rule.
Details
None is considered less than any Some- Two
Some values are compared using the provided Order
- Two
None values are equal (returns 0)
Example (Ordering Options)
import { Number as N, Option } from "effect"
const ord = Option.makeOrder(N.Order)
console.log(ord(Option.none(), Option.some(1)))
// Output: -1
console.log(ord(Option.some(1), Option.none()))
// Output: 1
console.log(ord(Option.some(1), Option.some(2)))
// Output: -1
makeOrder = <function (type parameter) A in <A>(O: Order<A>): Order<Option<A>>A>(type O: Order<A>O: interface Order<in A>Represents a total ordering for values of type A.
When to use
Use when you need to define how values of a type are compared.
Details
An order returns -1 when the first value is less than the second, 0 when
the values are equal according to this ordering, and 1 when the first value
is greater than the second. It must satisfy total ordering laws: totality,
antisymmetry, and transitivity.
Example (Defining a custom Order)
import { Order } from "effect"
const byAge: Order.Order<{ name: string; age: number }> = (self, that) => {
if (self.age < that.age) return -1
if (self.age > that.age) return 1
return 0
}
const person1 = { name: "Alice", age: 30 }
const person2 = { name: "Bob", age: 25 }
console.log(byAge(person1, person2)) // 1
Order<function (type parameter) A in <A>(O: Order<A>): Order<Option<A>>A>): interface Order<in A>Represents a total ordering for values of type A.
When to use
Use when you need to define how values of a type are compared.
Details
An order returns -1 when the first value is less than the second, 0 when
the values are equal according to this ordering, and 1 when the first value
is greater than the second. It must satisfy total ordering laws: totality,
antisymmetry, and transitivity.
Example (Defining a custom Order)
import { Order } from "effect"
const byAge: Order.Order<{ name: string; age: number }> = (self, that) => {
if (self.age < that.age) return -1
if (self.age > that.age) return 1
return 0
}
const person1 = { name: "Alice", age: 30 }
const person2 = { name: "Bob", age: 25 }
console.log(byAge(person1, person2)) // 1
Order<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>(O: Order<A>): Order<Option<A>>A>> =>
import orderorder.function make<A>(
compare: (self: A, that: A) => -1 | 0 | 1
): Order<A>
Creates a new Order instance from a comparison function.
When to use
Use when you need a sorting rule not covered by the built-in orders or input
mapping helpers, and you can provide a total comparison.
Details
Uses reference equality (===) as a shortcut: if self === that, it returns
0 without calling the comparison function. The comparison function should
return -1, 0, or 1, and the returned order satisfies total ordering
laws when the comparison function does.
Example (Creating an Order)
import { Order } from "effect"
const byAge = Order.make<{ name: string; age: number }>((self, that) => {
if (self.age < that.age) return -1
if (self.age > that.age) return 1
return 0
})
console.log(byAge({ name: "Alice", age: 30 }, { name: "Bob", age: 25 })) // 1
console.log(byAge({ name: "Alice", age: 25 }, { name: "Bob", age: 30 })) // -1
make((self: Option<A>self, that: Option<A>that) => 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<A>that) ? type O: Order<A>O(self: Some<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: Some<A>(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<A>.value: Avalue) : 1) : -1)