Update: min, max, minBy, maxBy (#65)

test/max.test.ts

@@ -0,0 +1,22 @@
+import { expectError, expectType } from 'tsd';
+
+import { max } from '../es';
+
+// please note how literals work in this situation
+expectType<1 | 2>(max(1, 2));
+// using variables that are type `number` is the more general use-case here
+const a: number = 1;
+const b: number = 2;
+expectType<number>(max(a, b));
+// you can also upcast inline to get the same result
+expectType<number>(max(1 as number, 2 as number));
+// now check the other Ord types
+expectType<string>(max('a' as string, 'b' as string));
+expectType<boolean>(max(true as boolean, false as boolean));
+expectType<Date>(max(new Date(Date.now() - 1), new Date(Date.now())));
+
+// curried
+expectType<(b: number) => number>(max(a));
+
+// don't allow different types
+expectError(max(1, '2'));

test/maxBy.test.ts

@@ -0,0 +1,34 @@
+import { expectError, expectType } from 'tsd';
+
+import { __, maxBy, prop } from '../es';
+
+type Obj = {
+  str: string;
+  date: Date;
+  bool: boolean;
+};
+
+// please note how literals work in this situation
+expectType<1 | 2>(maxBy(Math.abs, 1, 2));
+// using variables that are type `number` is the more general use-case here
+const a: number = 1;
+const b: number = 2;
+expectType<number>(maxBy(Math.abs, a, b));
+// you can also upcast inline to get the same result
+expectType<number>(maxBy(Math.abs, 1 as number, 2 as number));
+// now check the other Ord types
+expectType<Obj>(maxBy(prop('str'), {} as Obj, {} as Obj));
+expectType<Obj>(maxBy(prop('bool'), {} as Obj, {} as Obj));
+expectType<Obj>(maxBy(prop('date'), {} as Obj, {} as Obj));
+
+// Placeholder
+// expectType<number>(max(__, a, b)(fn));
+expectType<number>(maxBy(__, 1 as number, 2 as number)(Math.abs));
+// curried
+// notice how literals work fine here because `T` is pulled directly from Math.abs
+// in the full function typescript will hard union them, but here it cannot
+expectType<number>(maxBy(Math.abs)(1)(2));
+expectType<number>(maxBy(Math.abs)(1, 2));
+
+// don't allow different types
+expectError(maxBy(Math.abs, 1, '2'));

test/min.test.ts

@@ -0,0 +1,22 @@
+import { expectError, expectType } from 'tsd';
+
+import { min } from '../es';
+
+// please note how literals work in this situation
+expectType<1 | 2>(min(1, 2));
+// using variables that are type `number` is the more general use-case here
+const a: number = 1;
+const b: number = 2;
+expectType<number>(min(a, b));
+// you can also upcast inline to get the same result
+expectType<number>(min(1 as number, 2 as number));
+// now check the other Ord types
+expectType<string>(min('a' as string, 'b' as string));
+expectType<boolean>(min(true as boolean, false as boolean));
+expectType<Date>(min(new Date(Date.now() - 1), new Date(Date.now())));
+
+// curried
+expectType<(b: number) => number>(min(a));
+
+// don't allow different types
+expectError(min(1, '2'));

test/minBy.test.ts

@@ -0,0 +1,34 @@
+import { expectError, expectType } from 'tsd';
+
+import { __, minBy, prop } from '../es';
+
+type Obj = {
+  str: string;
+  date: Date;
+  bool: boolean;
+};
+
+// please note how literals work in this situation
+expectType<1 | 2>(minBy(Math.abs, 1, 2));
+// using variables that are type `number` is the more general use-case here
+const a: number = 1;
+const b: number = 2;
+expectType<number>(minBy(Math.abs, a, b));
+// you can also upcast inline to get the same result
+expectType<number>(minBy(Math.abs, 1 as number, 2 as number));
+// now check the other Ord types
+expectType<Obj>(minBy(prop('str'), {} as Obj, {} as Obj));
+expectType<Obj>(minBy(prop('bool'), {} as Obj, {} as Obj));
+expectType<Obj>(minBy(prop('date'), {} as Obj, {} as Obj));
+
+// Placeholder
+// expectType<number>(max(__, b)(a));
+expectType<number>(minBy(__, 1 as number, 2 as number)(Math.abs));
+// curried
+// notice how literals work fine here because `T` is pulled directly from Math.abs
+// in the full function typescript will hard union them, but here it cannot
+expectType<number>(minBy(Math.abs)(1)(2));
+expectType<number>(minBy(Math.abs)(1, 2));
+
+// don't allow different types
+expectError(minBy(Math.abs, 1, '2'));

types/maxBy.d.ts

@@ -1,6 +1,25 @@
-import * as _ from 'ts-toolbelt';
-import { Ord } from './util/tools';
+import { Placeholder, Ord } from './util/tools';
 
-export function maxBy<T>(keyFn: (a: T) => Ord): _.F.Curry<(a: T, b: T) => T>;
-export function maxBy<T>(keyFn: (a: T) => Ord, a: T): (b: T) => T;
-export function maxBy<T>(keyFn: (a: T) => Ord, a: T, b: T): T;
+// Commutative means we can simplify the overloads for handlings placeholders
+// maxBy(fn)
+export function maxBy<T>(fn: (a: T) => Ord): {
+  // maxBy(fn)(a)(b)
+  (a: T): (b: T) => T;
+  // maxBy(fn)(a, b)
+  (a: T, b: T): T;
+};
+// maxBy(__, a)
+export function maxBy<T>(__: Placeholder, a: T): {
+  // maxBy(__, a)(fn)(b)
+  (fn: (a: T) => Ord): (b: T) => T;
+  // maxBy(__, a)(__, b)(fn)
+  (__: Placeholder, b: T): (fn: (a: T) => Ord) => T;
+  // maxBy(__, a)(fn, b)
+  (fn: (a: T) => Ord, b: T): T;
+};
+// maxBy(fn, a)(b)
+export function maxBy<T>(fn: (a: T) => Ord, a: T): (b: T) => T;
+// maxBy(__, a, b)(fn)
+export function maxBy<T>(__: Placeholder, a: T, b: T): (fn: (a: T) => Ord) => T;
+// maxBy(fn, a, b)
+export function maxBy<T>(fn: (a: T) => Ord, a: T, b: T): T;

types/minBy.d.ts

@@ -1,6 +1,25 @@
-import * as _ from 'ts-toolbelt';
-import { Ord } from './util/tools';
+import { Placeholder, Ord } from './util/tools';
 
-export function minBy<T>(keyFn: (a: T) => Ord): _.F.Curry<(a: T, b: T) => T>;
-export function minBy<T>(keyFn: (a: T) => Ord, a: T): (b: T) => T;
-export function minBy<T>(keyFn: (a: T) => Ord, a: T, b: T): T;
+// Commutative means we can simplify the overloads for handlings placeholders
+// minBy(fn)
+export function minBy<T>(fn: (a: T) => Ord): {
+  // minBy(fn)(a)(b)
+  (a: T): (b: T) => T;
+  // minBy(fn)(a, b)
+  (a: T, b: T): T;
+};
+// minBy(__, a)
+export function minBy<T>(__: Placeholder, a: T): {
+  // minBy(__, a)(fn)(b)
+  (fn: (a: T) => Ord): (b: T) => T;
+  // minBy(__, a)(__, b)(fn)
+  (__: Placeholder, b: T): (fn: (a: T) => Ord) => T;
+  // minBy(__, a)(fn, b)
+  (fn: (a: T) => Ord, b: T): T;
+};
+// minBy(fn, a)(b)
+export function minBy<T>(fn: (a: T) => Ord, a: T): (b: T) => T;
+// minBy(__, a, b)(fn)
+export function minBy<T>(__: Placeholder, a: T, b: T): (fn: (a: T) => Ord) => T;
+// minBy(fn, a, b)
+export function minBy<T>(fn: (a: T) => Ord, a: T, b: T): T;