feat(util): introduce curry helper functions (#24)

Author: patrickmichalina

src/util/curry.ts

@@ -0,0 +1,50 @@
+export const curry2 =
+  <T1, T2, TReturn>(fn: (arg1: T1, arg2: T2) => TReturn) =>
+    (a1: T1) =>
+      (a2: T2) =>
+        fn(a1, a2)
+
+export const curry3 =
+  <T1, T2, T3, TReturn>(fn: (arg1: T1, arg2: T2, arg3: T3) => TReturn) =>
+    (a1: T1) =>
+      (a2: T2) =>
+        (a3: T3) =>
+          fn(a1, a2, a3)
+
+export const curry4 =
+  <T1, T2, T3, T4, TReturn>(fn: (arg1: T1, arg2: T2, arg3: T3, arg4: T4) => TReturn) =>
+    (a1: T1) =>
+      (a2: T2) =>
+        (a3: T3) =>
+          (a4: T4) =>
+            fn(a1, a2, a3, a4)
+
+export const curry5 =
+  <T1, T2, T3, T4, T5, TReturn>(fn: (arg1: T1, arg2: T2, arg3: T3, arg4: T4, arg5: T5) => TReturn) =>
+    (a1: T1) =>
+      (a2: T2) =>
+        (a3: T3) =>
+          (a4: T4) =>
+            (a5: T5) =>
+              fn(a1, a2, a3, a4, a5)
+
+export const curry6 =
+  <T1, T2, T3, T4, T5, T6, TReturn>(fn: (arg1: T1, arg2: T2, arg3: T3, arg4: T4, arg5: T5, arg6: T6) => TReturn) =>
+    (a1: T1) =>
+      (a2: T2) =>
+        (a3: T3) =>
+          (a4: T4) =>
+            (a5: T5) =>
+              (a6: T6) =>
+                fn(a1, a2, a3, a4, a5, a6)
+
+export const curry7 =
+  <T1, T2, T3, T4, T5, T6, T7, TReturn>(fn: (arg1: T1, arg2: T2, arg3: T3, arg4: T4, arg5: T5, arg6: T6, arg7: T7) => TReturn) =>
+    (a1: T1) =>
+      (a2: T2) =>
+        (a3: T3) =>
+          (a4: T4) =>
+            (a5: T5) =>
+              (a6: T6) =>
+                (a7: T7) =>
+                  fn(a1, a2, a3, a4, a5, a6, a7)

src/util/index.ts

@@ -1 +1,9 @@
-export { maybeEnv } from './maybe-env'
+export { maybeEnv } from './maybe-env'
+export {
+  curry2,
+  curry3,
+  curry4,
+  curry5,
+  curry6,
+  curry7
+} from './curry'

test/util/curry.spec.ts

@@ -0,0 +1,50 @@
+import { curry2, curry3, curry4, curry5, curry6, curry7 } from '../../src/util/curry'
+
+describe('curry', () => {
+  it('should work with 2 arguments', () => {
+    const add = (a: number, b: number) => a + b
+    const add1to = curry2(add)(1)
+    
+    expect(add1to(2)).toEqual(3)
+  })
+
+  it('should work with 3 arguments', () => {
+    const add = (a: number, b: number, c: number) => a + b + c
+    const addCurried = curry3(add)
+    const add3to = addCurried(1)(2)
+    
+    expect(add3to(2)).toEqual(5)
+  })
+
+  it('should work with 4 arguments', () => {
+    const add = (a: number, b: number, c: number, d: number) => a + b + c + d
+    const addCurried = curry4(add)
+    const add3to = addCurried(1)(1)(1)
+    
+    expect(add3to(2)).toEqual(5)
+  })
+
+  it('should work with 5 arguments', () => {
+    const add = (a: number, b: number, c: number, d: number, e: number) => a + b + c + d + e
+    const addCurried = curry5(add)
+    const add4to = addCurried(1)(1)(1)(1)
+    
+    expect(add4to(1)).toEqual(5)
+  })
+
+  it('should work with 6 arguments', () => {
+    const add = (a: number, b: number, c: number, d: number, e: number, f: number) => a + b + c + d + e + f
+    const addCurried = curry6(add)
+    const add5to = addCurried(1)(1)(1)(1)(1)
+    
+    expect(add5to(1)).toEqual(6)
+  })
+
+  it('should work with 7 arguments', () => {
+    const add = (a: number, b: number, c: number, d: number, e: number, f: number, g: number) => a + b + c + d + e + f + g
+    const addCurried = curry7(add)
+    const add6to = addCurried(1)(1)(1)(1)(1)(1)
+    
+    expect(add6to(1)).toEqual(7)
+  })
+})