fix(liftFN): fix multiple bugs and resolve ramda complatibility issue

Closes #59

package.json

@@ -4,7 +4,7 @@
   "name": "ramda-adjunct",
   "description": "Extensions for Ramda",
   "keywords": "ramda extensions addons cookbook adjunct recipe extras",
-  "version": "1.4.0",
+  "version": "1.3.2",
   "homepage": "https://github.com/char0n/ramda-adjunct",
   "license": "SEE LICENSE IN LICENSE.md",
   "repository": {
@@ -104,5 +104,8 @@
     "typescript": "=2.2.2",
     "webpack": "=2.4.1"
   },
-  "tonicExampleFilename": "tonicExample.js"
+  "tonicExampleFilename": "tonicExample.js",
+  "dependencies": {
+    "fantasy-land": "=3.2.0"
+  }
 }

src/index.d.ts

@@ -234,13 +234,13 @@ declare namespace RamdaAdjunct {
 
         /**
          * "lifts" a function to be the specified arity, so that it may "map over" objects that satisfy
-         * the Apply spec of algebraic structures.
+         * the Apply spec of fantasy land.
          */
         liftFN<T>(arity: number, fn: Variadic<Apply, T>): Apply
 
         /**
          * "lifts" a function of arity > 1 so that it may "map over" objects that satisfy
-         * the Apply spec of algebraic structures.
+         * the Apply spec of fantasy land.
          */
         liftF<T>(fn: Variadic<Apply, T>): Apply
     }

src/liftF.js

@@ -1,13 +1,14 @@
 import liftFN from './liftFN';
 
 /**
- * "lifts" a function of arity > 1 so that it may "map over" objects that satisfy
- * the Apply spec of algebraic structures. This function is not compatible
- * with {@link https://github.com/fantasyland/fantasy-land#apply|FantasyLand Apply spec}.
+ * "lifts" a function to be the specified arity, so that it may "map over" objects that satisfy
+ * the fantasy land Apply spec of algebraic structures.
  *
  * Lifting is specific for {@link https://github.com/scalaz/scalaz|scalaz} and {@link http://www.functionaljava.org/|functional java} implementations.
- * One of the mainstream libraries that uses this Apply spec is {@link https://cwmyers.github.io/monet.js/|monet.js}.
- * This function acts as interop for ramda and monet.js.
+ * Old version of fantasy land spec were not compatible with this approach,
+ * but as of fantasy land 1.0.0 Apply spec also adopted this approach.
+ *
+ * This function acts as interop for ramda <= 0.23.0 and {@link https://cwmyers.github.io/monet.js/|monet.js}.
  *
  * More info {@link https://github.com/fantasyland/fantasy-land/issues/50|here}.
  *

src/liftFN.js

@@ -1,13 +1,54 @@
-import { curry, last, slice, reverse, reduce, pipe, ap, curryN, map, flip } from 'ramda';
+import fantasyLand from 'fantasy-land';
+import { curry, head, slice, reduce, ap as apR, curryN, map, add, flip } from 'ramda';
+
+
+const applicativeTrait = {
+  of(value) {
+    return { ...this, value };
+  },
+};
+applicativeTrait[fantasyLand.of] = applicativeTrait.of;
+
+const functorTrait = {
+  map(fn) {
+    return this.of(fn(this.value));
+  },
+};
+functorTrait[fantasyLand.map] = functorTrait.map;
+
+const applyTrait = {
+  ap(monadWithApplyOfAFunction) {
+    return monadWithApplyOfAFunction.map(fn => fn(this.value));
+  },
+};
+applyTrait[fantasyLand.ap] = applyTrait.ap;
+
+const Monad = { ...applicativeTrait, ...functorTrait, ...applyTrait };
+const m1 = Monad.of(1);
+const m2 = Monad.of(2).map(add);
+
+
+export const createAp = (ap1, ap2) => {
+  try {
+    // new version of `ap` starting from ramda version > 0.23.0
+    return ap1.ap(ap2) && apR;
+  } catch (e) {
+    // old version of `ap` till ramda version <= 0.23.0
+    return curryN(2, flip(apR));
+  }
+};
+
+const ap = createAp(m2, m1);
 
 /**
  * "lifts" a function to be the specified arity, so that it may "map over" objects that satisfy
- * the Apply spec of algebraic structures. This function is not compatible
- * with {@link https://github.com/fantasyland/fantasy-land#apply|FantasyLand Apply spec}.
+ * the fantasy land Apply spec of algebraic structures.
  *
  * Lifting is specific for {@link https://github.com/scalaz/scalaz|scalaz} and {@link http://www.functionaljava.org/|functional java} implementations.
- * One of the mainstream libraries that uses this Apply spec is {@link https://cwmyers.github.io/monet.js/|monet.js}.
- * This function acts as interop for ramda and monet.js.
+ * Old version of fantasy land spec were not compatible with this approach,
+ * but as of fantasy land 1.0.0 Apply spec also adopted this approach.
+ *
+ * This function acts as interop for ramda <= 0.23.0 and {@link https://cwmyers.github.io/monet.js/|monet.js}.
  *
  * More info {@link https://github.com/fantasyland/fantasy-land/issues/50|here}.
  *
@@ -33,9 +74,9 @@ import { curry, last, slice, reverse, reduce, pipe, ap, curryN, map, flip } from
 const liftFN = curry((arity, fn) => {
   const lifted = curryN(arity, fn);
   return curryN(arity, (...args) => {
-    const accumulator = map(lifted, last(args));
-    const apps = pipe(slice(0, arity - 1), reverse)(args);
-    return reduce(flip(ap), accumulator, apps);
+    const accumulator = map(lifted, head(args));
+    const apps = slice(1, Infinity, args);
+    return reduce(ap, accumulator, apps);
   });
 });
 

test/liftF.js

@@ -1,12 +1,11 @@
 import { Maybe } from 'monet';
-import { curry } from 'ramda';
 
 import RA from '../src/index';
 import eq from './shared/eq';
 
-const add3 = curry((a, b, c) => a + b + c);
-const add4 = curry((a, b, c, d) => a + b + c + d);
-const add5 = curry((a, b, c, d, e) => a + b + c + d + e);
+const add3 = (a, b, c) => a + b + c;
+const add4 = (a, b, c, d) => a + b + c + d;
+const add5 = (a, b, c, d, e) => a + b + c + d + e;
 
 describe('liftF', function() {
   const addF3 = RA.liftF(add3);

test/liftFN.js

@@ -1,12 +1,13 @@
+import chai from 'chai';
 import { Maybe } from 'monet';
-import { add, reduce, curry } from 'ramda';
+import { add, reduce } from 'ramda';
 
 import RA from '../src/index';
 import eq from './shared/eq';
 
 
 const addN = (...args) => reduce(add, 0, args);
-const add3 = curry((a, b, c) => a + b + c);
+const add3 = (a, b, c) => a + b + c;
 
 describe('liftFN', function() {
   const addN3 = RA.liftFN(3, addN);
@@ -18,7 +19,14 @@ describe('liftFN', function() {
   });
 
   it('limits a variadic function to the specified arity', function() {
-    eq(addN3(Maybe.Some(1), Maybe.Some(1), Maybe.Some(1), Maybe.Some(1)), Maybe.Some(3));
+    eq(addN3(Maybe.Some(1), Maybe.Some(1), Maybe.Some(1)), Maybe.Some(3));
+  });
+
+  it('throws error on variadic function is more arguments than arity', function() {
+    chai.assert.throws(
+      addN3.bind(null, Maybe.Some(1), Maybe.Some(1), Maybe.Some(1), Maybe.Some(1)),
+      TypeError
+    );
   });
 
   it('can lift functions of any arity', function() {
@@ -30,6 +38,10 @@ describe('liftFN', function() {
     );
   });
 
+  it('retain order of arguments', function() {
+    eq(RA.liftFN(3, add3)(Maybe.Some('a'), Maybe.Some('b'), Maybe.Some('c')), Maybe.Some('abc'));
+  });
+
   it('is curried', function() {
     const f4 = RA.liftFN(4);
     eq(typeof f4, 'function');