More library functions

src/list.ts

@@ -31,8 +31,13 @@ export const append: L<<T extends P>(l: List<T>) => L<(r: List<T>) => List<T>>>
 export const concat: L<<T extends P>(ls: List<List<T>>) => List<T>>
   = _(ls => ls._(Nil)._(_(x => _(xs => append._(x)._(concat._(xs))))));
 
-export const repeat: L<<T extends P>(v: T) => List<T>>
-  = _(v => cons._(v)._(repeat._(v)));
+export const repeat: L<<T extends P>(x: T) => List<T>>
+  = _(x => cons._(x)._(repeat._(x)));
+
+export const iterate: L<<T extends P>(f: L<(x: T) => T>) => L<(x: T) => List<T>>>
+  = _(<T extends P>(f: L<(x: T) => T>) =>
+    _((x: T) =>
+      cons._(x)._(iterate._(f)._(f._(x)))));
 
 export const head: L<<T extends P>(xs: List<T>) => T>
   = _(xs => xs._(undef)._(_(x => _(_xs => x))));

src/string.ts

@@ -7,7 +7,7 @@ import { Cons, List, Nil, cmp as cmpl, concat, cons, eq as eql, ge as gel, gt as
 
 export type String = List<Char>;
 
-export { Nil as Empty, nul as empty, len, Cons, cons, snoc, append, get, update, set } from './list';
+export { Nil as Empty, nul as empty, len, Cons, cons, snoc, append, repeat, iterate, get, update, set } from './list';
 
 export const cmp: L<(l: String) => L<(r: String) => Ord>>
   = cmpl._(cmpc);

test/list.spec.ts

@@ -4,12 +4,11 @@ import { toNOrd as $o, NOrd } from '../src/ord';
 import { toBoolean as $b, iif } from '../src/bool';
 import { toNumber as $n, toNumber as $nn, Num, Succ, Zero, fromNumber as _n, fromNumber as _nn, cmp as cmpn, eq as eqn, even, gt as ngt, show as nshow, odd, succ, sum } from '../src/num';
 import { toChar as $c } from '../src/char';
-import { toArray as $a, Cons, List, Nil, fromArray as _a, all, any, append, cmp, concat, cons, eq, filter, foldl, foldlz, foldr, foldrz, ge, get, gt, head, intersperse, le, len, lt, map, nul, set, show, snoc, tail, update } from '../src/list';
+import { toArray as $a, Cons, List, Nil, fromArray as _a, all, any, append, cmp, concat, cons, eq, filter, foldl, foldlz, foldr, foldrz, ge, get, gt, head, intersperse, iterate, le, len, lt, map, nul, set, show, snoc, tail, update } from '../src/list';
 import { toString as $s } from '../src/string';
 
 describe('List', () => {
-  const iterate: (n: Num) => List<Num> = n => new L(() => Cons._(n)._(iterate(Succ._(n))).value);
-  const infinite: List<Num> = iterate(Zero);
+  const infinite: List<Num> = iterate._(Succ)._(Zero);
 
   const _na: (xs: number[]) => List<Num>
     = xs => xs.length === 0 ? Nil : Cons._(_nn(xs[0]))._(new L(() => _na(xs.slice(1)).value));
@@ -163,6 +162,15 @@ describe('List', () => {
   //   });
   // });
 
+  // describe('iterate', () => {
+  //   it('iterate succ 0 is [0, 1, 2, ...]', () => {
+  //     expect($na(
+  //       iterate._(_n(0))._<List<Num>>(_((x0: Num) => _((x1s: List<Num>) =>
+  //         x1s._<List<Num>>(_((x1: Num) => _((x2s: List<Num>) =>
+  //           x2s._<List<Num>>(_((x2: Num) => _((_xrs: List<Num>): List<Num> => cons._(x0)._(cons._(x1)._(cons._(x2)._(Nil)))))))))))))).toEqual([0, 1, 2]);
+  //   });
+  // });
+
   describe('head', () => {
     it('returns nothing from Nil', () => {
       expect(() => $$(head._(Nil))).toThrow();

test/string.spec.ts

@@ -37,6 +37,25 @@ describe('String', () => {
     });
   });
 
+ // describe('repeat', () => {
+  //   it('repeat "a" is "aaa..."', () => {
+  //     expect($na(
+  //       repeat._(_s('a'))._<String>(_((x0: Char) => _((x1s: String) =>
+  //         x1s._<String>(_((x1: Char) => _((x2s: String) =>
+  //           x2s._<String>(_((x2: Char) => _((_xrs: String): String => cons._(x0)._(cons._(x1)._(cons._(x2)._(Nil)))))))))))))).toEqual('aaa');
+  //   });
+  // });
+
+  // describe('iterate', () => {
+  //   it('iterate succ "a" is "abc..."', () => {
+  //     expect($na(
+  //       iterate._(_s('a'))._<String>(_((x0: Char) => _((x1s: String) =>
+  //         x1s._<String>(_((x1: Char) => _((x2s: String) =>
+  //           x2s._<String>(_((x2: Char) => _((_xrs: String): String => cons._(x0)._(cons._(x1)._(cons._(x2)._(Nil)))))))))))))).toEqual('abc');
+  //   });
+  // });
+
+
   describe('empty', () => {
     it('empty "" is True', () => {
       expect($b(empty._(_s('')))).toEqual(true);