feat: functional programming

functional-programming.js/compose-function.js

@@ -0,0 +1,21 @@
+const f = n => n * 2;
+const g = n => n + 1;
+const h = x => f(g(x));
+
+console.log(h(20))
+
+// Algebra function composition
+/**
+ * g: a -> b
+ * f: b -> c
+ * h: a -> c
+ * f(g(x)) = h(x)
+ */
+
+const compose2 = (f, g) => x => f(g(x));
+
+console.log(compose2(n => n * 2, n => n + 1)(20))
+
+const compose = (...fns) => x => fns.reduceRight((y, f) => f(y), x);
+
+console.log(compose2(n => n * 2, n => n + 1)(20))

functional-programming.js/curry-function.js

@@ -0,0 +1,3 @@
+const add = a => b => a + b;
+
+console.log(add(5)(5));