feature: add omitIndexes (char0n#180)

Closes char0n#174

src/index.d.ts

@@ -557,6 +557,12 @@ declare namespace RamdaAdjunct {
         sliceTo<T>(toIndex: number, list: string|Array<T>): string|Array<T>;
         sliceTo(toIndex: number): <T>(list: string|Array<T>) => string|Array<T>;
 
+        /**
+         * Returns a partial copy of an array omitting the indexes specified.
+         */
+        omitIndexes<T>(indexes: number[], list: Array<T>): Array<T>;
+        omitIndexes(indexes: number[]): <T>(list: Array<T>) => Array<T>;
+
          /**
          * Identity type.
          */

src/index.js

@@ -67,6 +67,7 @@ import reduceP from './reduceP';
 import reduceRightP from './reduceRightP';
 import sliceFrom from './sliceFrom';
 import sliceTo from './sliceTo';
+import omitIndexes from './omitIndexes';
 // Object
 import paths from './paths';
 import renameKeys from './renameKeys';
@@ -162,6 +163,7 @@ export { default as reduceP } from './reduceP';
 export { default as reduceRightP } from './reduceRightP';
 export { default as sliceFrom } from './sliceFrom';
 export { default as sliceTo } from './sliceTo';
+export { default as omitIndexes } from './omitIndexes';
 // Object
 export { default as paths } from './paths';
 export { default as renameKeys } from './renameKeys';
@@ -262,6 +264,7 @@ const RA = {
   reduceRightP,
   sliceFrom,
   sliceTo,
+  omitIndexes,
   // Object
   defaults: mergeRight,
   resetToDefault: mergeRight,

src/omitIndexes.js

@@ -0,0 +1,25 @@
+import { contains, curry, addIndex, reject } from 'ramda';
+
+// helpers
+const rejectIndexed = addIndex(reject);
+const containsIndex = curry((indexes, val, index) => contains(index, indexes));
+
+/**
+ * Returns a partial copy of an array omitting the indexes specified.
+ *
+ * @func omitIndexes
+ * @memberOf RA
+ * @since {@link https://char0n.github.io/ramda-adjunct/1.19.0|v1.19.0}
+ * @category List
+ * @sig [i] -> [a] -> [a]
+ * @see {@link http://ramdajs.com/docs/#omit|omit}
+ * @param {!Array} indexes The array of indexes to omit from the new array
+ * @param {!Array} list The array to copy from
+ * @return {!Array} The new array with indexes not on it
+ * @example
+ *
+ * RA.omitIndexes([-1, 1, 3], ['a', 'b', 'c', 'd']); //=> ['a', 'c']
+ */
+const omitIndexes = curry((indexes, list) => rejectIndexed(containsIndex(indexes), list));
+
+export default omitIndexes;

test/omitIndexes.js

@@ -0,0 +1,46 @@
+import RA from '../src/index';
+import eq from './shared/eq';
+
+
+describe('omitIndexes', function() {
+  it('tests currying', function () {
+    const indexes = [1, 3];
+    const arr = ['a', 'b', 'c', 'd'];
+    const expected = ['a', 'c'];
+
+    eq(RA.omitIndexes(indexes, arr), expected);
+    eq(RA.omitIndexes(indexes)(arr), expected);
+  });
+
+  it('tests non existing indexes are omitted', function() {
+    const indexes = [-1, 1, 3];
+    const arr = ['a', 'b', 'c', 'd'];
+    const expected = ['a', 'c'];
+
+    eq(RA.omitIndexes(indexes, arr), expected);
+  });
+
+  it('tests when empty indexes', function() {
+    const indexes = [];
+    const arr = ['a', 'b', 'c', 'd'];
+    const expected = arr;
+
+    eq(RA.omitIndexes(indexes, arr), expected);
+  });
+
+  it('tests when empty list', function() {
+    const indexes = [1, 3];
+    const arr = [];
+    const expected = arr;
+
+    eq(RA.omitIndexes(indexes, arr), expected);
+  });
+
+  it('tests when empty indexes and list', function() {
+    const indexes = [];
+    const arr = [];
+    const expected = arr;
+
+    eq(RA.omitIndexes(indexes, arr), expected);
+  });
+});