feat: add isTruthy

Ref #66

src/index.d.ts

@@ -626,6 +626,13 @@ declare namespace RamdaAdjunct {
          */
         isPromise(val: any): val is Promise<any>;
 
+        /**
+         * In JavaScript, a `truthy` value is a value that is considered true
+         * when evaluated in a Boolean context. All values are truthy unless
+         * they are defined as falsy (i.e., except for `false`, `0`, `""`, `null`, `undefined`, and `NaN`).
+         */
+        isTruthy(val: any): boolean;
+
          /**
          * Identity type.
          */

src/index.js

@@ -59,6 +59,7 @@ export { default as isPair } from './isPair';
 export { default as isNotPair } from './isNotPair';
 export { default as isThenable } from './isThenable';
 export { default as isPromise } from './isPromise';
+export { default as isTruthy } from './isTruthy';
 // Function
 export { default as stubUndefined } from './stubUndefined';
 export { default as stubNull } from './stubNull';

src/isTruthy.js

@@ -0,0 +1,29 @@
+import { pipe, equals } from 'ramda';
+
+
+/**
+ * In JavaScript, a `truthy` value is a value that is considered true
+ * when evaluated in a Boolean context. All values are truthy unless
+ * they are defined as falsy (i.e., except for `false`, `0`, `""`, `null`, `undefined`, and `NaN`).
+ *
+ * @func isTruthy
+ * @memberOf RA
+ * @since {@link https://char0n.github.io/ramda-adjunct/2.2.0|v2.2..0}
+ * @category Type
+ * @sig * -> Boolean
+ * @param {*} val The value to test
+ * @return {Boolean}
+ * @see {@link RA.isFalsy|isFalsy}
+ * @example
+ *
+ * RA.isTruthy({}); // => true
+ * RA.isTruthy([]); // => true
+ * RA.isTruthy(42); // => true
+ * RA.isTruthy(3.14); // => true
+ * RA.isTruthy('foo'); // => true
+ * RA.isTruthy(new Date()); // => true
+ * RA.isTruthy(Infinity); // => true
+ */
+const isTruthy = pipe(Boolean, equals(true));
+
+export default isTruthy;

test/isTruthy.js

@@ -0,0 +1,32 @@
+import * as RA from '../src/index';
+import eq from './shared/eq';
+import Symbol from './shared/Symbol';
+import args from './shared/arguments';
+
+
+describe('isTruthy', function() {
+  it('tests a value for `truthy`', function() {
+    eq(RA.isTruthy('abc'), true);
+    eq(RA.isTruthy(Object('abc')), true);
+    eq(RA.isTruthy(args), true);
+    eq(RA.isTruthy([1, 2, 3]), true);
+    eq(RA.isTruthy(true), true);
+    eq(RA.isTruthy(new Date()), true);
+    eq(RA.isTruthy(new Error()), true);
+    eq(RA.isTruthy(Array.prototype.slice), true);
+    eq(RA.isTruthy({ 0: 1, length: 1 }), true);
+    eq(RA.isTruthy(1), true);
+    eq(RA.isTruthy(/x/), true);
+    eq(RA.isTruthy(Symbol), true);
+    eq(RA.isTruthy({}), true);
+    eq(RA.isTruthy([]), true);
+    eq(RA.isTruthy(Infinity), true);
+
+    eq(RA.isTruthy(false), false);
+    eq(RA.isTruthy(0), false);
+    eq(RA.isTruthy(''), false);
+    eq(RA.isTruthy(null), false);
+    eq(RA.isTruthy(undefined), false);
+    eq(RA.isTruthy(NaN), false);
+  });
+});