✨ PoC on new currying (#298)

**Issue :** fix #297

packages/immutadot/src/core/curry.js

@@ -0,0 +1,17 @@
+export function curry(fn, minArity = fn.length) {
+  function curried(prevArgs) {
+    return (...args) => {
+      if (prevArgs.length >= minArity - 1)
+        return fn(args[0], ...prevArgs)
+
+      return curried(prevArgs.concat(args))
+    }
+  }
+
+  return (...args) => {
+    if (args.length >= minArity)
+      return fn(...args)
+
+    return curried(args)
+  }
+}

packages/immutadot/src/core/curry.spec.js

@@ -0,0 +1,28 @@
+/* eslint-env jest */
+import { curry } from './curry'
+
+describe('curry.curry', () => {
+  function fill(obj, path, value, start = 0, end = -1, extraArg) {
+    return `fill(${obj}, ${path}, ${value}, ${start}, ${end}, ${extraArg})`
+  }
+  const curriedFill = curry(fill)
+
+  it('should allow non curried calls', () => {
+    expect(curriedFill('obj', 'path', 'value')).toBe('fill(obj, path, value, 0, -1, undefined)')
+    expect(curriedFill('obj', 'path', 'value', 1)).toBe('fill(obj, path, value, 1, -1, undefined)')
+    expect(curriedFill('obj', 'path', 'value', 1, 2)).toBe('fill(obj, path, value, 1, 2, undefined)')
+    expect(curriedFill('obj', 'path', 'value', 1, 2, 'extraArg')).toBe('fill(obj, path, value, 1, 2, extraArg)')
+  })
+
+  it('should allow all sorts of curried calls', () => {
+    expect(curriedFill('path', 'value')('obj')).toBe('fill(obj, path, value, 0, -1, undefined)')
+    expect(curriedFill('path')('value')('obj')).toBe('fill(obj, path, value, 0, -1, undefined)')
+    expect(curriedFill('path')('value', 1)('obj')).toBe('fill(obj, path, value, 1, -1, undefined)')
+    expect(curriedFill('path')('value', 1, 2)('obj')).toBe('fill(obj, path, value, 1, 2, undefined)')
+    expect(curriedFill('path')('value', 1, 2, 'extraArg')('obj')).toBe('fill(obj, path, value, 1, 2, extraArg)')
+  })
+
+  it('should discard extra args in last curried call', () => {
+    expect(curriedFill('path', 'value')('obj', 'extraArg')).toBe('fill(obj, path, value, 0, -1, undefined)')
+  })
+})