// ets_tracing: off

/**
 * adapted from https://github.com/gcanti/fp-ts
 */
import "../../../Operator";
import { identity } from "../../../Function/core";
import { isSome, none, some } from "../../../Option";
import * as Tp from "../Tuple";
/**
 * Classic Applicative's ap
 */

export function ap(fa) {
  return fab => ap_(fab, fa);
}
/**
 * Classic Applicative's ap
 */

export function ap_(fab, fa) {
  return flatten(map(f => map(f)(fa))(fab));
}
/**
 * Composes computations in sequence, using the return value of one computation to determine the next computation.
 */

export function chain(f) {
  return ma => chain_(ma, f);
}
/**
 * Composes computations in sequence, using the return value of one computation to determine the next computation.
 */

export function chain_(fa, f) {
  let resLen = 0;
  const l = fa.length;
  const temp = new Array(l);

  for (let i = 0; i < l; i++) {
    const e = fa[i];
    const arr = f(e);
    resLen += arr.length;
    temp[i] = arr;
  }

  const r = Array(resLen);
  let start = 0;

  for (let i = 0; i < l; i++) {
    const arr = temp[i];
    const l = arr.length;

    for (let j = 0; j < l; j++) {
      r[j + start] = arr[j];
    }

    start += l;
  }

  return r;
}
/**
 * Like chain but ignores output
 */

export function tap(f) {
  return ma => tap_(ma, f);
}
/**
 * Like chain but ignores output
 */

export function tap_(ma, f) {
  return chain_(ma, a => map(() => a)(f(a)));
}
/**
 * A useful recursion pattern for processing an array to produce a new array, often used for "chopping" up the input
 * array. Typically chop is called with some function that will consume an initial prefix of the array and produce a
 * value and the rest of the array.
 */

export function chop(f) {
  return as => chop_(as, f);
}
/**
 * A useful recursion pattern for processing an array to produce a new array, often used for "chopping" up the input
 * array. Typically chop is called with some function that will consume an initial prefix of the array and produce a
 * value and the rest of the array.
 */

export function chop_(as, f) {
  const result = [];
  let cs = as;

  while (isNonEmpty(cs)) {
    const {
      tuple: [b, c]
    } = f(cs);
    result.push(b);
    cs = c;
  }

  return result;
}
/**
 * Splits an array into length-`n` pieces. The last piece will be shorter if `n` does not evenly divide the length of
 * the array. Note that `chunksOf(n)([])` is `[]`, not `[[]]`. This is intentional, and is consistent with a recursive
 * definition of `chunksOf`; it satisfies the property that
 *
 * ```ts
 * chunksOf(n)(xs).concat(chunksOf(n)(ys)) == chunksOf(n)(xs.concat(ys)))
 * ```
 *
 * whenever `n` evenly divides the length of `xs`.
 */

export function chunksOf(n) {
  return as => chunksOf_(as, n);
}
/**
 * Splits an array into length-`n` pieces. The last piece will be shorter if `n` does not evenly divide the length of
 * the array. Note that `chunksOf(n)([])` is `[]`, not `[[]]`. This is intentional, and is consistent with a recursive
 * definition of `chunksOf`; it satisfies the property that
 *
 * ```ts
 * chunksOf(n)(xs).concat(chunksOf(n)(ys)) == chunksOf(n)(xs.concat(ys)))
 * ```
 *
 * whenever `n` evenly divides the length of `xs`.
 */

export function chunksOf_(as, n) {
  const f = chop(splitAt(n));
  return as.length === 0 ? empty : isOutOfBound(n - 1, as) ? [as] : f(as);
}
/**
 * Filter out optional values
 */

export function compact(fa) {
  return filterMap(x => x)(fa);
}
export function comprehension(input, f, g = () => true) {
  const go = (scope, input) => {
    if (input.length === 0) {
      return g(...scope) ? [f(...scope)] : empty;
    } else {
      return chain(x => go(snoc_(scope, x), input.slice(1)))(input[0]);
    }
  };

  return go(empty, input);
}
/**
 * Concatenate
 */

export function concat_(x, y) {
  const lenx = x.length;

  if (lenx === 0) {
    return y;
  }

  const leny = y.length;

  if (leny === 0) {
    return x;
  }

  const r = Array(lenx + leny);

  for (let i = 0; i < lenx; i++) {
    r[i] = x[i];
  }

  for (let i = 0; i < leny; i++) {
    r[i + lenx] = y[i];
  }

  return r;
}
/**
 * Concatenate
 */

export function concat(y) {
  return x => concat_(x, y);
}
/**
 * Concatenate strictly
 */

export function concatS_(x, y) {
  return concat_(x, y);
}
/**
 * Concatenate strictly
 */

export function concatS(y) {
  return x => concatS_(x, y);
}
/**
 * Attaches an element to the front of an array, creating a new non empty array
 *
 * ```ts
 * assert.deepStrictEqual(cons(0, [1, 2, 3]), [0, 1, 2, 3])
 * ```
 */

export function cons_(tail, head) {
  const len = tail.length;
  const r = Array(len + 1);

  for (let i = 0; i < len; i++) {
    r[i + 1] = tail[i];
  }

  r[0] = head;
  return r;
}
/**
 * Attaches an element to the front of an array, creating a new non empty array
 */

export function cons(head) {
  return tail => cons_(tail, head);
}
/**
 * Delete the element at the specified index, creating a new array, or returning `None` if the index is out of bounds
 *
 * ```ts
 * assert.deepStrictEqual(deleteAt(0)([1, 2, 3]), some([2, 3]))
 * assert.deepStrictEqual(deleteAt(1)([]), none)
 * ```
 */

export function deleteAt(i) {
  return as => deleteAt_(as, i);
}
/**
 * Delete the element at the specified index, creating a new array, or returning `None` if the index is out of bounds
 */

export function deleteAt_(as, i) {
  return isOutOfBound(i, as) ? none : some(unsafeDeleteAt_(as, i));
}
/**
 * Drop a number of elements from the start of an array, creating a new array
 *
 * ```ts
 * assert.deepStrictEqual(dropLeft(2)([1, 2, 3]), [3])
 * ```
 */

export function dropLeft(n) {
  return as => dropLeft_(as, n);
}
/**
 * Drop a number of elements from the start of an array, creating a new array
 */

export function dropLeft_(as, n) {
  return as.slice(n, as.length);
}
/**
 * Remove the longest initial subarray for which all element satisfy the specified predicate, creating a new array
 *
 * ```ts
 * assert.deepStrictEqual(dropLeftWhile((n: number) => n % 2 === 1)([1, 3, 2, 4, 5]), [2, 4, 5])
 * ```
 */

export function dropLeftWhile(predicate) {
  return as => dropLeftWhile_(as, predicate);
}
/**
 * Remove the longest initial subarray for which all element satisfy the specified predicate, creating a new array
 *
 * ```
 * assert.deepStrictEqual(dropLeftWhile((n: number) => n % 2 === 1)([1, 3, 2, 4, 5]), [2, 4, 5])
 * ```
 */

export function dropLeftWhile_(as, predicate) {
  const i = spanIndex_(as, predicate);
  const l = as.length;
  const rest = Array(l - i);

  for (let j = i; j < l; j++) {
    rest[j - i] = as[j];
  }

  return rest;
}
/**
 * Drop a number of elements from the end of an array, creating a new array
 *
 * ```
 * assert.deepStrictEqual(dropRight(2)([1, 2, 3, 4, 5]), [1, 2, 3])
 * ```
 */

export function dropRight(n) {
  return as => dropRight_(as, n);
}
/**
 * Drop a number of elements from the end of an array, creating a new array
 *
 * ```
 * assert.deepStrictEqual(dropRight(2)([1, 2, 3, 4, 5]), [1, 2, 3])
 * ```
 */

export function dropRight_(as, n) {
  return as.slice(0, as.length - n);
}
/**
 * Array[A] => Array[Array[A]]
 */

export function duplicate(ma) {
  return extend(x => x)(ma);
}
/**
 * An empty array
 */

export const empty = [];
/**
 * An empty array
 */

export const emptyOf = () => [];
/**
 * Extends calls f with all the progressive slices up to the current element's index,
 * and uses the return value to construct the result array
 *
 * i.e: like map that also consumes all the elements up to `i`
 */

export function extend(f) {
  return ma => extend_(ma, f);
}
/**
 * Extends calls f with all the progressive slices up to the current element's index,
 * and uses the return value to construct the result array
 *
 * i.e: like map that also consumes all the elements up to `i`
 */

export function extend_(ma, f) {
  return ma.map((_, i, as) => f(as.slice(i)));
}
export function filter(predicate) {
  return fa => fa.filter(predicate);
}
export function filter_(fa, predicate) {
  return fa.filter(predicate);
}
/**
 * Filters the array also passing element index
 */

export function filterWithIndex(predicate) {
  return nea => filterWithIndex_(nea, predicate);
}
/**
 * Filters the array also passing element index
 */

export function filterWithIndex_(nea, predicate) {
  return nea.filter((a, i) => predicate(i, a));
}
/**
 * Filters the array also mapping the output
 */

export const filterMap = f => fa => filterMap_(fa, f);
/**
 * Filters the array also mapping the output
 */

export function filterMap_(fa, f) {
  return filterMapWithIndex_(fa, (_, a) => f(a));
}
/**
 * Filters the array also mapping the output
 */

export function filterMapWithIndex(f) {
  return fa => filterMapWithIndex_(fa, f);
}
/**
 * Filters the array also mapping the output
 */

export function filterMapWithIndex_(fa, f) {
  const result = [];

  for (let i = 0; i < fa.length; i++) {
    const optionB = f(i, fa[i]);

    if (isSome(optionB)) {
      result.push(optionB.value);
    }
  }

  return result;
}
/**
 * Maps an array until `none` is returned
 */

export function collectWhileMap_(arr, f) {
  const result = [];

  for (let i = 0; i < arr.length; i++) {
    const o = f(arr[i]);

    if (isSome(o)) {
      result.push(o.value);
    } else {
      break;
    }
  }

  return result;
}
/**
 * Maps an array until `none` is returned
 */

export function collectWhileMap(f) {
  return arr => collectWhileMap_(arr, f);
}
export function findFirst(predicate) {
  return as => findFirst_(as, predicate);
}
export function findFirst_(as, predicate) {
  const len = as.length;

  for (let i = 0; i < len; i++) {
    if (predicate(as[i])) {
      return some(as[i]);
    }
  }

  return none;
}
/**
 * Find the first element returned by an option based selector function
 *
 * ```ts
 * interface Person {
 *   name: string
 *   age?: number
 * }
 *
 * const persons: Array<Person> = [{ name: 'John' }, { name: 'Mary', age: 45 }, { name: 'Joey', age: 28 }]
 *
 * // returns the name of the first person that has an age
 * assert.deepStrictEqual(findFirstMap((p: Person) => (p.age === undefined ? none : some(p.name)))(persons), some('Mary'))
 * ```
 */

export function findFirstMap(f) {
  return as => findFirstMap_(as, f);
}
/**
 * Find the first element returned by an option based selector function
 */

export function findFirstMap_(as, f) {
  const len = as.length;

  for (let i = 0; i < len; i++) {
    const v = f(as[i]);

    if (isSome(v)) {
      return v;
    }
  }

  return none;
}
/**
 * Find the first index for which a predicate holds
 *
 * ```
 * assert.deepStrictEqual(findIndex((n: number) => n === 2)([1, 2, 3]), some(1))
 * assert.deepStrictEqual(findIndex((n: number) => n === 2)([]), none)
 * ```
 */

export function findIndex(predicate) {
  return as => findIndex_(as, predicate);
}
/**
 * Find the first index for which a predicate holds
 */

export function findIndex_(as, predicate) {
  const len = as.length;

  for (let i = 0; i < len; i++) {
    if (predicate(as[i])) {
      return some(i);
    }
  }

  return none;
}
export function findLast(predicate) {
  return as => findLast_(as, predicate);
}
export function findLast_(as, predicate) {
  const len = as.length;

  for (let i = len - 1; i >= 0; i--) {
    if (predicate(as[i])) {
      return some(as[i]);
    }
  }

  return none;
}
/**
 * Returns the index of the last element of the list which matches the predicate
 *
 * ```ts
 * interface X {
 *   a: number
 *   b: number
 * }
 * const xs: Array<X> = [{ a: 1, b: 0 }, { a: 1, b: 1 }]
 * assert.deepStrictEqual(findLastIndex((x: { a: number }) => x.a === 1)(xs), some(1))
 * assert.deepStrictEqual(findLastIndex((x: { a: number }) => x.a === 4)(xs), none)
 * ```
 */

export function findLastIndex(predicate) {
  return as => findLastIndex_(as, predicate);
}
/**
 * Returns the index of the last element of the list which matches the predicate
 */

export function findLastIndex_(as, predicate) {
  const len = as.length;

  for (let i = len - 1; i >= 0; i--) {
    if (predicate(as[i])) {
      return some(i);
    }
  }

  return none;
}
/**
 * Find the last element returned by an option based selector function
 *
 * ```ts
 * interface Person {
 *   name: string
 *   age?: number
 * }
 *
 * const persons: Array<Person> = [{ name: 'John' }, { name: 'Mary', age: 45 }, { name: 'Joey', age: 28 }]
 *
 * // returns the name of the last person that has an age
 * assert.deepStrictEqual(findLastMap((p: Person) => (p.age === undefined ? none : some(p.name)))(persons), some('Joey'))
 * ```
 */

export function findLastMap(f) {
  return as => findLastMap_(as, f);
}
/**
 * Find the last element returned by an option based selector function
 */

export function findLastMap_(as, f) {
  const len = as.length;

  for (let i = len - 1; i >= 0; i--) {
    const v = f(as[i]);

    if (isSome(v)) {
      return v;
    }
  }

  return none;
}
/**
 * Removes one level of nesting
 *
 * ```ts
 * assert.deepStrictEqual(flatten([[1], [2], [3]]), [1, 2, 3])
 * ```
 */

export function flatten(mma) {
  return chain_(mma, identity);
}
/**
 * Break an array into its first element and remaining elements
 *
 * ```ts
 * const len: <A>(as: Array<A>) => number = foldLeft(() => 0, (_, tail) => 1 + len(tail))
 * assert.strictEqual(len([1, 2, 3]), 3)
 * ```
 */

export function foldLeft(onNil, onCons) {
  return as => foldLeft_(as, onNil, onCons);
}
/**
 * Break an array into its first element and remaining elements
 */

export function foldLeft_(as, onNil, onCons) {
  return isEmpty(as) ? onNil() : onCons(as[0], as.slice(1));
}
/**
 * Break an array into its initial elements and the last element
 */

export function foldRight(onNil, onCons) {
  return as => foldRight_(as, onNil, onCons);
}
/**
 * Break an array into its initial elements and the last element
 */

export function foldRight_(as, onNil, onCons) {
  return isEmpty(as) ? onNil() : onCons(as.slice(0, as.length - 1), as[as.length - 1]);
}
/**
 * Copies a mutable array into an immutable
 */

export function fromMutable(as) {
  const l = as.length;

  if (l === 0) {
    return empty;
  }

  const ras = Array(l);

  for (let i = 0; i < l; i++) {
    ras[i] = as[i];
  }

  return ras;
}
/**
 * Get the first element in an array, or `None` if the array is empty
 *
 * ```ts
 * assert.deepStrictEqual(head([1, 2, 3]), some(1))
 * assert.deepStrictEqual(head([]), none)
 * ```
 */

export function head(as) {
  return isEmpty(as) ? none : some(as[0]);
}
/**
 * Get all but the last element of an array, creating a new array, or `None` if the array is empty
 *
 * ```
 * assert.deepStrictEqual(init([1, 2, 3]), some([1, 2]))
 * assert.deepStrictEqual(init([]), none)
 * ```
 */

export function init(as) {
  const len = as.length;
  return len === 0 ? none : some(as.slice(0, len - 1));
}
/**
 * Insert an element at the specified index, creating a new array, or returning `None` if the index is out of bounds
 *
 * ```
 * assert.deepStrictEqual(insertAt(2, 5)([1, 2, 3, 4]), some([1, 2, 5, 3, 4]))
 * ```
 */

export function insertAt(i, a) {
  return as => insertAt_(as, i, a);
}
/**
 * Insert an element at the specified index, creating a new array, or returning `None` if the index is out of bounds
 */

export function insertAt_(as, i, a) {
  return i < 0 || i > as.length ? none : some(unsafeInsertAt_(as, i, a));
}
/**
 * Test whether an array is empty
 *
 * ```
 * assert.strictEqual(isEmpty([]), true)
 * ```
 */

export function isEmpty(as) {
  return as.length === 0;
}
/**
 * Test whether an array is non empty narrowing down the type to `NonEmptyArray<A>`
 */

export function isNonEmpty(as) {
  return as.length > 0;
}
/**
 * Test whether an array contains a particular index
 */

export function isOutOfBound(i, as) {
  return i < 0 || i >= as.length;
}
/**
 * Get the last element in an array, or `None` if the array is empty
 *
 * ```ts
 * assert.deepStrictEqual(last([1, 2, 3]), some(3))
 * assert.deepStrictEqual(last([]), none)
 * ```
 */

export function last(as) {
  return lookup_(as, as.length - 1);
}
/**
 * Extracts from an array of `Either` all the `Left` elements. All the `Left` elements are extracted in order
 *
 * ```ts
 * assert.deepStrictEqual(lefts([right(1), left('foo'), right(2)]), ['foo'])
 * ```
 */

export function lefts(as) {
  const r = [];
  const len = as.length;

  for (let i = 0; i < len; i++) {
    const a = as[i];

    if (a._tag === "Left") {
      r.push(a.left);
    }
  }

  return r;
}
/**
 * This function provides a safe way to read a value at a particular index from an array
 *
 * ```ts
 * assert.deepStrictEqual(lookup(1, [1, 2, 3]), some(2))
 * assert.deepStrictEqual(lookup(3, [1, 2, 3]), none)
 * ```
 */

export function lookup_(as, i) {
  return isOutOfBound(i, as) ? none : some(as[i]);
}
/**
 * This function provides a safe way to read a value at a particular index from an array
 */

export function lookup(i) {
  return as => lookup_(as, i);
}
/**
 * Return a list of length `n` with element `i` initialized with `f(i)`
 *
 * ```ts
 * const double = (n: number): number => n * 2
 * assert.deepStrictEqual(makeBy_(5, double), [0, 2, 4, 6, 8])
 * ```
 */

export function makeBy_(n, f) {
  const r = [];

  for (let i = 0; i < n; i++) {
    r.push(f(i));
  }

  return r;
}
/**
 * Return a list of length `n` with element `i` initialized with `f(i)`
 */

export function makeBy(f) {
  return n => makeBy_(n, f);
}
/**
 * Apply f to every element of Array<A> returning Array<B>
 */

export function map(f) {
  return fa => fa.map(f);
}
/**
 * Apply f to every element of Array<A> returning Array<B>
 */

export function map_(fa, f) {
  return fa.map(f);
}
/**
 * Like map but also passes the index to f
 */

export function mapWithIndex(f) {
  return fa => mapWithIndex_(fa, f);
}
/**
 * Like map but also passes the index to f
 */

export function mapWithIndex_(fa, f) {
  return fa.map((a, i) => f(i, a));
}
/**
 * Apply a function to the element at the specified index, creating a new array, or returning `None` if the index is out
 * of bounds
 *
 * ```ts
 * const double = (x: number): number => x * 2
 * assert.deepStrictEqual(modifyAt(1, double)([1, 2, 3]), some([1, 4, 3]))
 * assert.deepStrictEqual(modifyAt(1, double)([]), none)
 * ```
 */

export function modifyAt(i, f) {
  return as => isOutOfBound(i, as) ? none : some(unsafeUpdateAt_(as, i, f(as[i])));
}
/**
 * Apply a function to the element at the specified index, creating a new array, or returning `None` if the index is out
 * of bounds
 */

export function modifyAt_(as, i, f) {
  return isOutOfBound(i, as) ? none : some(unsafeUpdateAt_(as, i, f(as[i])));
}
/**
 * Construct an array with a single element
 */

export function single(a) {
  return [a];
}
/**
 * Create an array containing a range of integers, including both endpoints
 *
 * ```ts
 * assert.deepStrictEqual(range(1, 5), [1, 2, 3, 4, 5])
 * ```
 */

export function range(start, end) {
  return makeBy_(end - start + 1, i => start + i);
}
/**
 * Construct B by compacting with f over the array from left to right
 */

export function reduce(b, f) {
  return fa => reduce_(fa, b, f);
}
/**
 * Construct B by compacting with f over the array from left to right
 */

export function reduce_(fa, b, f) {
  return reduceWithIndex_(fa, b, (_, b, a) => f(b, a));
}
/**
 * Construct B by compacting with f over the array from right to left
 */

export function reduceRight(b, f) {
  return fa => reduceRight_(fa, b, f);
}
/**
 * Construct B by compacting with f over the array from right to left
 */

export function reduceRight_(fa, b, f) {
  return reduceRightWithIndex_(fa, b, (_, a, b) => f(a, b));
}
/**
 * Construct B by compacting with f over the array from right to left
 */

export function reduceRightWithIndex(b, f) {
  return fa => fa.reduceRight((b, a, i) => f(i, a, b), b);
}
/**
 * Construct B by compacting with f over the array from right to left
 */

export function reduceRightWithIndex_(fa, b, f) {
  return fa.reduceRight((b, a, i) => f(i, a, b), b);
}
/**
 * Construct B by compacting with f over the array from left to right
 */

export function reduceWithIndex(b, f) {
  return fa => reduceWithIndex_(fa, b, f);
}
/**
 * Construct B by compacting with f over the array from left to right
 */

export function reduceWithIndex_(fa, b, f) {
  const l = fa.length;
  let r = b;

  for (let i = 0; i < l; i++) {
    r = f(i, r, fa[i]);
  }

  return r;
}
/**
 * Create an array containing a value repeated the specified number of times
 *
 * ```ts
 * assert.deepStrictEqual(replicate_(3, 'a'), ['a', 'a', 'a'])
 * ```
 */

export function replicate_(n, a) {
  return makeBy_(n, () => a);
}
/**
 * Create an array containing a value repeated the specified number of times
 *
 * ```ts
 * assert.deepStrictEqual(replicate_(3, 'a'), ['a', 'a', 'a'])
 * ```
 */

export function replicate(a) {
  return n => replicate_(n, a);
}
/**
 * Reverse an array, creating a new array
 *
 * ```ts
 * assert.deepStrictEqual(reverse([1, 2, 3]), [3, 2, 1])
 * ```
 */

export function reverse(as) {
  return [...as].reverse();
}
/**
 * Extracts from an array of `Either` all the `Right` elements. All the `Right` elements are extracted in order
 *
 * ```ts
 * assert.deepStrictEqual(rights([right(1), left('foo'), right(2)]), [1, 2])
 * ```
 */

export function rights(as) {
  const r = [];
  const len = as.length;

  for (let i = 0; i < len; i++) {
    const a = as[i];

    if (a._tag === "Right") {
      r.push(a.right);
    }
  }

  return r;
}
/**
 * Rotate an array to the right by `n` steps
 *
 * ```ts
 * assert.deepStrictEqual(rotate(2)([1, 2, 3, 4, 5]), [4, 5, 1, 2, 3])
 * ```
 */

export function rotate(n) {
  return as => rotate_(as, n);
}
/**
 * Rotate an array to the right by `n` steps
 */

export function rotate_(as, n) {
  const len = as.length;

  if (n === 0 || len <= 1 || len === Math.abs(n)) {
    return as;
  } else if (n < 0) {
    return rotate(len + n)(as);
  } else {
    return as.slice(-n).concat(as.slice(0, len - n));
  }
}
/**
 * Same as `reduce` but it carries over the intermediate steps
 *
 * ```ts
 * import { scanLeft } from '@matechs/core/Array'
 *
 * assert.deepStrictEqual(scanLeft(10, (b, a: number) => b - a)([1, 2, 3]), [10, 9, 7, 4])
 * ```
 */

export function scanLeft(b, f) {
  return as => scanLeft_(as, b, f);
}
/**
 * Same as `reduce` but it carries over the intermediate steps
 */

export function scanLeft_(as, b, f) {
  const l = as.length;
  const r = new Array(l + 1);
  r[0] = b;

  for (let i = 0; i < l; i++) {
    r[i + 1] = f(r[i], as[i]);
  }

  return r;
}
/**
 * Fold an array from the right, keeping all intermediate results instead of only the final result
 *
 * ```ts
 * assert.deepStrictEqual(scanRight(10, (a: number, b) => b - a)([1, 2, 3]), [4, 5, 7, 10])
 * ```
 */

export function scanRight(b, f) {
  return as => scanRight_(as, b, f);
}
/**
 * Fold an array from the right, keeping all intermediate results instead of only the final result
 */

export function scanRight_(as, b, f) {
  const l = as.length;
  const r = new Array(l + 1);
  r[l] = b;

  for (let i = l - 1; i >= 0; i--) {
    r[i] = f(as[i], r[i + 1]);
  }

  return r;
}
/**
 * Append an element to the end of an array, creating a new non empty array
 *
 * ```ts
 * assert.deepStrictEqual(snoc([1, 2, 3], 4), [1, 2, 3, 4])
 * ```
 */

export function snoc_(init, end) {
  const len = init.length;
  const r = Array(len + 1);

  for (let i = 0; i < len; i++) {
    r[i] = init[i];
  }

  r[len] = end;
  return r;
}
/**
 * Append an element to the end of an array, creating a new non empty array
 */

export function snoc(end) {
  return init => snoc_(init, end);
}
/**
 * Finds the first index that doesn't satisfy predicate or the length of as
 */

export const spanIndex_ = (as, predicate) => {
  const l = as.length;
  let i = 0;

  for (; i < l; i++) {
    if (!predicate(as[i])) {
      break;
    }
  }

  return i;
};
export function spanLeft(predicate) {
  return as => spanLeft_(as, predicate);
}
export function spanLeft_(as, predicate) {
  const i = spanIndex_(as, predicate);
  const init = Array(i);

  for (let j = 0; j < i; j++) {
    init[j] = as[j];
  }

  const l = as.length;
  const rest = Array(l - i);

  for (let j = i; j < l; j++) {
    rest[j - i] = as[j];
  }

  return {
    init,
    rest
  };
}
/**
 * Splits an array into two pieces, the first piece has `n` elements.
 *
 * ```ts
 * assert.deepStrictEqual(splitAt(2)([1, 2, 3, 4, 5]), [[1, 2], [3, 4, 5]])
 * ```
 */

export function splitAt(n) {
  return as => Tp.tuple(as.slice(0, n), as.slice(n));
}
/**
 * Splits an array into two pieces, the first piece has `n` elements.
 */

export function splitAt_(as, n) {
  return Tp.tuple(as.slice(0, n), as.slice(n));
}
/**
 * Get all but the first element of an array, creating a new array, or `None` if the array is empty
 *
 * ```ts
 * assert.deepStrictEqual(tail([1, 2, 3]), some([2, 3]))
 * assert.deepStrictEqual(tail([]), none)
 * ```
 */

export function tail(as) {
  return isEmpty(as) ? none : some(as.slice(1));
}
/**
 * Keep only a number of elements from the start of an array, creating a new array.
 * `n` must be a natural number
 *
 * ```ts
 * assert.deepStrictEqual(takeLeft(2)([1, 2, 3]), [1, 2])
 * ```
 */

export function takeLeft(n) {
  return as => as.slice(0, n);
}
/**
 * Keep only a number of elements from the start of an array, creating a new array.
 * `n` must be a natural number
 */

export function takeLeft_(as, n) {
  return as.slice(0, n);
}
export function takeLeftWhile(predicate) {
  return as => takeLeftWhile_(as, predicate);
}
export function takeLeftWhile_(as, predicate) {
  const i = spanIndex_(as, predicate);
  const init = Array(i);

  for (let j = 0; j < i; j++) {
    init[j] = as[j];
  }

  return init;
}
export function takeUntil(predicate) {
  return as => takeUntil_(as, predicate);
}
export function takeUntil_(as, predicate) {
  const init = [];

  for (let i = 0; i < as.length; i++) {
    init[i] = as[i];

    if (predicate(as[i])) {
      return init;
    }
  }

  return init;
}
/**
 * Keep only a number of elements from the end of an array, creating a new array.
 * `n` must be a natural number
 *
 * ```ts
 * assert.deepStrictEqual(takeRight(2)([1, 2, 3, 4, 5]), [4, 5])
 * ```
 */

export function takeRight(n) {
  return as => takeRight_(as, n);
}
/**
 * Keep only a number of elements from the end of an array, creating a new array.
 * `n` must be a natural number
 */

export function takeRight_(as, n) {
  return n === 0 ? empty : as.slice(-n);
}
/**
 * Copies this array into a mutable one
 */

export function toMutable(ras) {
  const l = ras.length;
  const as = Array(l);

  for (let i = 0; i < l; i++) {
    as[i] = ras[i];
  }

  return as;
}
/**
 * Construct A by unfolding B signaling end with an option
 */

export function unfold_(b, f) {
  const ret = [];
  let bb = b; // eslint-disable-next-line no-constant-condition

  while (true) {
    const mt = f(bb);

    if (isSome(mt)) {
      const [a, b] = mt.value.tuple;
      ret.push(a);
      bb = b;
    } else {
      break;
    }
  }

  return ret;
}
/**
 * Construct A by unfolding B signaling end with an option
 */

export function unfold(f) {
  return b => unfold_(b, f);
}
/**
 * Deletes index i (non safe)
 */

export function unsafeDeleteAt_(as, i) {
  const xs = [...as];
  xs.splice(i, 1);
  return xs;
}
/**
 * Deletes index i (non safe)
 */

export function unsafeDeleteAt(i) {
  return as => unsafeDeleteAt_(as, i);
}
/**
 * Inserts index i (non safe)
 */

export function unsafeInsertAt_(as, i, a) {
  const xs = [...as];
  xs.splice(i, 0, a);
  return xs;
}
/**
 * Inserts index i (non safe)
 */

export function unsafeInsertAt(i, a) {
  return as => unsafeInsertAt_(as, i, a);
}
/**
 * Updates index i (non safe)
 */

export function unsafeUpdateAt_(as, i, a) {
  if (as[i] === a) {
    return as;
  } else {
    const xs = [...as];
    xs[i] = a;
    return xs;
  }
}
/**
 * Updates index i (non safe)
 */

export function unsafeUpdateAt(i, a) {
  return as => unsafeUpdateAt_(as, i, a);
}
/**
 * The function is reverse of `zip`. Takes an array of pairs and return two corresponding arrays
 *
 * ```ts
 * assert.deepStrictEqual(unzip([[1, 'a'], [2, 'b'], [3, 'c']]), [[1, 2, 3], ['a', 'b', 'c']])
 * ```
 */

export function unzip(as) {
  const fa = [];
  const fb = [];

  for (let i = 0; i < as.length; i++) {
    fa[i] = as[i].get(0);
    fb[i] = as[i].get(1);
  }

  return Tp.tuple(fa, fb);
}
/**
 * Change the element at the specified index, creating a new array, or returning `None` if the index is out of bounds
 *
 * ```ts
 * assert.deepStrictEqual(updateAt(1, 1)([1, 2, 3]), some([1, 1, 3]))
 * assert.deepStrictEqual(updateAt(1, 1)([]), none)
 * ```
 */

export function updateAt(i, a) {
  return as => updateAt_(as, i, a);
}
/**
 * Change the element at the specified index, creating a new array, or returning `None` if the index is out of bounds
 */

export function updateAt_(as, i, a) {
  return isOutOfBound(i, as) ? none : some(unsafeUpdateAt_(as, i, a));
}
/**
 * Takes two arrays and returns an array of corresponding pairs. If one input array is short, excess elements of the
 * longer array are discarded
 *
 * ```ts
 * assert.deepStrictEqual(zip([1, 2, 3], ['a', 'b', 'c', 'd']), [[1, 'a'], [2, 'b'], [3, 'c']])
 * ```
 */

export function zip(fb) {
  return zipWith(fb, Tp.tuple);
}
/**
 * Takes two arrays and returns an array of corresponding pairs. If one input array is short, excess elements of the
 * longer array are discarded
 */

export function zip_(fa, fb) {
  return zipWith_(fa, fb, Tp.tuple);
}
/**
 * Apply a function to pairs of elements at the same index in two arrays, collecting the results in a new array. If one
 * input array is short, excess elements of the longer array are discarded.
 *
 * ```ts
 * assert.deepStrictEqual(zipWith([1, 2, 3], ['a', 'b', 'c', 'd'], (n, s) => s + n), ['a1', 'b2', 'c3'])
 * ```
 */

export function zipWith_(fa, fb, f) {
  const fc = [];
  const len = Math.min(fa.length, fb.length);

  for (let i = 0; i < len; i++) {
    fc[i] = f(fa[i], fb[i]);
  }

  return fc;
}
/**
 * Apply a function to pairs of elements at the same index in two arrays, collecting the results in a new array. If one
 * input array is short, excess elements of the longer array are discarded.
 */

export function zipWith(fb, f) {
  return fa => zipWith_(fa, fb, f);
}
/**
 * Separate Array
 */

export function separate(fa) {
  const left = [];
  const right = [];

  for (const e of fa) {
    if (e._tag === "Left") {
      left.push(e.left);
    } else {
      right.push(e.right);
    }
  }

  return {
    left,
    right
  };
}
/**
 * Drops elements while the predicate returns true
 */

export function dropWhile_(as, predicate) {
  const i = spanIndex_(as, predicate);
  const l = as.length;
  const rest = Array(l - i);

  for (let j = i; j < l; j++) {
    rest[j - i] = as[j];
  }

  return rest;
}
/**
 * Drops elements while the predicate returns true
 */

export function dropWhile(predicate) {
  return as => dropWhile_(as, predicate);
}
/**
 * Constructs a new readonly array from an interable.
 */

export function from(as) {
  return Array.from(as);
}
/**
 * Joins together string arrays
 */

export function join_(as, s) {
  return as.join(s);
}
/**
 * Joins together string arrays
 */

export function join(s) {
  return as => as.join(s);
}
/**
 * Splits an array into sub-non-empty-arrays stored in an object, based on the result of calling a `string`-returning
 * function on each element, and grouping the results according to values returned
 */

export function groupBy(f) {
  return as => groupBy_(as, f);
}
/**
 * Splits an array into sub-non-empty-arrays stored in an object, based on the result of calling a `string`-returning
 * function on each element, and grouping the results according to values returned
 */

export function groupBy_(as, f) {
  const r = {};

  for (const a of as) {
    const k = f(a); // eslint-disable-next-line no-prototype-builtins

    if (r.hasOwnProperty(k)) {
      r[k].push(a);
    } else {
      r[k] = [a];
    }
  }

  return r;
}
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