Implement nand

src/index.d.ts

@@ -979,6 +979,12 @@ declare namespace RamdaAdjunct {
          */
         neither(firstPredicate: Function, secondPredicate: Function): Function;
 
+        /**
+         * Returns true if both arguments are falsy; false otherwise.
+         */
+        nand(a: any, b: any): Boolean;
+        nand(a: any): (b: any) => Boolean;
+
         /**
          * Takes a list of predicates and returns a predicate that returns true for a given list of
          * arguments if one or more of the provided predicates is not satisfied by those arguments.

src/index.js

@@ -161,6 +161,7 @@ export { default as inRange } from './inRange';
 export { default as isNotEmpty } from './isNotEmpty';
 export { default as defaultWhen } from './defaultWhen';
 export { default as notBoth } from './notBoth';
+export { default as nand } from './nand';
 export { default as neither } from './neither';
 export { default as notAllPass } from './notAllPass';
 export { default as nonePass } from './nonePass';

src/nand.js

@@ -0,0 +1,27 @@
+import { and, complement } from 'ramda';
+
+/**
+ * Returns true if both arguments are falsy; false otherwise.
+ *
+ * @func nand
+ * @memberOf RA
+ * @since {@link https://char0n.github.io/ramda-adjunct/2.19.0|v2.19.0}
+ * @category Logic
+ * @sig a -> b -> Boolean
+ * @param {Boolean} a
+ * @param {Boolean} b
+ * @return {Boolean} true if both arguments are false
+ * @example
+ *
+ * RA.nand(true, true); //=> false
+ * RA.nand(false, true); //=> true
+ * RA.nand(true, false); //=> true
+ * RA.nand(false, false); //=> true
+ * RA.nand(1.0, 1.0); //=> false
+ * RA.nand(1.0, 0); //=> true
+ * RA.nand(0, 1.0); //=> true
+ * RA.nand(0, 0); //=> true
+ */
+const nand = complement(and); // eslint-disable-line ramda/complement-simplification
+
+export default nand;

test/nand.js

@@ -0,0 +1,38 @@
+import eq from './shared/eq';
+import * as RA from '../src';
+
+describe('RA.nand', function() {
+  it('should work on booleans', function() {
+    eq(RA.nand(true, true), false);
+    eq(RA.nand(false, true), true);
+    eq(RA.nand(true, false), true);
+    eq(RA.nand(false, false), true);
+  });
+
+  it('should work on numbers', function() {
+    eq(RA.nand(1.0, 1.0), false);
+    eq(RA.nand(0.0, 1.0), true);
+    eq(RA.nand(1.0, 0.0), true);
+    eq(RA.nand(0.0, 0.0), true);
+  });
+
+  it('should work on a combination of things', function() {
+    eq(RA.nand(true, 1.0), false);
+    eq(RA.nand(null, true), true);
+    eq(RA.nand(1.0, undefined), true);
+    eq(RA.nand(0.0, false), true);
+    eq(RA.nand(null, null), true);
+    eq(RA.nand(null, undefined), true);
+  });
+
+  it('should support currying', function() {
+    eq(RA.nand(true, true), false);
+    eq(RA.nand(true)(true), false);
+    eq(RA.nand(false, true), true);
+    eq(RA.nand(false)(true), true);
+    eq(RA.nand(true, false), true);
+    eq(RA.nand(true)(false), true);
+    eq(RA.nand(false, false), true);
+    eq(RA.nand(false)(false), true);
+  });
+});