tests

src/pair.js

@@ -48,12 +48,13 @@ export class Pair<A, B> {
 	}
 
 	/**
-	 * `map :: Pair a b ~> ([a, b] -> [x, y]) -> Pair x y`
+	 * `map :: Pair a b ~> (b -> c) -> Pair a c`
 	 *
-	 * Transforms the values in the `Pair` instance.
+	 * Transforms the right (second) value in the `Pair` instance.
 	 */
-	map<X, Y>(f: (p: [A, B]) => [X, Y]): Pair<X, Y> {
-		return Pair.of(f(this.data));
+	map<C>(f: (b: B) => C): Pair<A, C> {
+		const [ a, b ] = this.data;
+		return Pair.of([ a, f(b) ]);
 	}
 
 	/**

test/io.js

@@ -6,7 +6,7 @@ import * as Util from './test-util';
 const ioMapper = <A>(ia: IO<A>): A => ia.runIO();
 
 test('IO', t => {
-	t.plan(5);
+	t.plan(6);
 
 	const tIO = { t, mapper: ioMapper };
 
@@ -15,4 +15,6 @@ test('IO', t => {
 	Util.testLift(tIO, IO);
 	Util.testLift2(tIO, IO);
 	Util.testLift3(tIO, IO);
+
+	t.equal(IO.from(() => 42).runIO(), 42, 'IO.from');
 });

test/pair.js

@@ -3,7 +3,7 @@ import { Pair } from '../src/pair';
 import test from 'tape';
 
 test('Pair', t => {
-	t.plan(4);
+	t.plan(7);
 
 	let pair = Pair.of([ 'foo', 42 ]);
 
@@ -18,9 +18,12 @@ test('Pair', t => {
 	);
 
 	t.deepEqual(
-		pair.map(([ s, n ]) => [s.toUpperCase(), n * 2]),
-		Pair.of([ 'FOO', 84 ]),
+		pair.map(n => n * 2),
+		Pair.of([ 'foo', 84 ]),
 		'Pair.map'
 	);
 
+	t.deepEqual(pair.toTuple(), [ 'foo', 42 ], 'pair.toTuple');
+	t.equal(pair.left(), 'foo', 'pair.left');
+	t.equal(pair.right(), 42, 'pair.right');
 });