hkt-toolbelt/natural-number-theory/fibonacci-sequence.d.ts

Functional and composable type utilities

import { $, Conditional, Kind, List, Loop, NaturalNumber } from '..';
type GetLastTwo = $<Kind.Juxt, [$<Kind.Pipe, [List.Pop, List.Last]>, List.Last]>;
type SumLastTwo = $<Kind.Pipe, [GetLastTwo, $<Kind.Uncurry, NaturalNumber.Add>]>;
type AppendNewSum = $<Kind.Pipe, [
    $<Kind.Juxt, [SumLastTwo, List.PushValue]>,
    $<Kind.Uncurry, Kind.Apply>
]>;
type LengthIsX = $<Kind.PipeWeak, [
    Conditional.Equals,
    $<List.PushValue, [List.Length]>,
    Kind.Pipe
]>;
/**
 * `FibonacciSequence` is a type-level function that generates a sequence of
 * Fibonacci numbers, given a desired resultant length, and an initial sequence.
 *
 * @example
 * ```ts
 * import { $, NaturalNumberTheory } from "hkt-toolbelt";
 *
 * type Result = $<
 *   $<NaturalNumberTheory.FibonacciSequence, 5>,
 *   [0, 1]
 * >; // [0, 1, 1, 2, 3]
 * ```
 */
export type FibnonacciSequence = $<Kind.PipeWeak, [
    LengthIsX,
    Loop.Until,
    $<Kind.Apply, AppendNewSum>
]>;
export {};