♻️ refactor(convolution): Extract generic implementation.

Author: make-github-pseudonymous-again

src/_convolution.js

@@ -0,0 +1,23 @@
+import {_window} from '@iterable-iterator/window';
+import {_chain} from '@iterable-iterator/chain';
+import {nrepeat} from '@iterable-iterator/repeat';
+import {map, starmap} from '@iterable-iterator/map';
+import {_zip2} from '@iterable-iterator/zip';
+import {reduce} from '@iterable-iterator/reduce';
+
+/**
+ * _convolution.
+ *
+ * @param {Array} rKernel
+ * @param {Iterable} signal
+ * @return {IterableIterator}
+ */
+const _convolution = (rKernel, signal, {add, mul, zero}) => {
+	const n = rKernel.length;
+	return map(
+		(slidingWindow) => reduce(add, starmap(mul, _zip2(rKernel, slidingWindow))),
+		_window(n, _chain([nrepeat(zero, n - 1), signal, nrepeat(zero, n - 1)])),
+	);
+};
+
+export default _convolution;

src/convolution.js

@@ -1,20 +1,17 @@
-import {_window} from '@iterable-iterator/window';
-import {_chain} from '@iterable-iterator/chain';
-import {nrepeat} from '@iterable-iterator/repeat';
 import {list} from '@iterable-iterator/list';
 import {reversed} from '@iterable-iterator/reversed';
-import {map, starmap} from '@iterable-iterator/map';
-import {mul} from '@functional-abstraction/operator';
-import {_zip2} from '@iterable-iterator/zip';
-import {sum} from '@iterable-iterator/reduce';
+import {add, mul} from '@functional-abstraction/operator';
 
-const convolution = (kernel, signal) => {
-	const rKernel = list(reversed(kernel));
-	const n = rKernel.length;
-	return map(
-		(slidingWindow) => sum(starmap(mul, _zip2(rKernel, slidingWindow))),
-		_window(n, _chain([nrepeat(0, n - 1), signal, nrepeat(0, n - 1)])),
-	);
-};
+import _convolution from './_convolution.js';
+
+/**
+ * Convolution.
+ *
+ * @param {Iterable} kernel
+ * @param {Iterable} signal
+ * @return {IterableIterator}
+ */
+const convolution = (kernel, signal) =>
+	_convolution(list(reversed(kernel)), signal, {add, mul, zero: 0});
 
 export default convolution;

src/index.js

@@ -1 +1,2 @@
+export {default as _convolution} from './_convolution.js';
 export {default as convolution} from './convolution.js';