Add fast failure to encase and fromPromise

Closes #91

src/encase.js

@@ -56,28 +56,26 @@ export function attempt(f){
 }
 
 export function encase(f, x){
-  if(arguments.length === 1) return partial1(encase, f);
   if(!isFunction(f)) invalidArgument('Future.encase', 0, 'be a function', f);
+  if(arguments.length === 1) return partial1(encase, f);
   return new Encase(f, x);
 }
 
 export function encase2(f, x, y){
+  if(!isFunction(f)) invalidArgument('Future.encase2', 0, 'be a function', f);
   switch(arguments.length){
     case 1: return partial1(encase2, f);
     case 2: return partial2(encase2, f, x);
-    default:
-      if(!isFunction(f)) invalidArgument('Future.encase2', 0, 'be a function', f);
-      return new Encase(f, x, y);
+    default: return new Encase(f, x, y);
   }
 }
 
 export function encase3(f, x, y, z){
+  if(!isFunction(f)) invalidArgument('Future.encase3', 0, 'be a function', f);
   switch(arguments.length){
     case 1: return partial1(encase3, f);
     case 2: return partial2(encase3, f, x);
     case 3: return partial3(encase3, f, x, y);
-    default:
-      if(!isFunction(f)) invalidArgument('Future.encase3', 0, 'be a function', f);
-      return new Encase(f, x, y, z);
+    default: return new Encase(f, x, y, z);
   }
 }

src/from-promise.js

@@ -51,28 +51,26 @@ FromPromise.prototype.toString = function FromPromise$toString(){
 };
 
 export function fromPromise(f, x){
-  if(arguments.length === 1) return partial1(fromPromise, f);
   if(!isFunction(f)) invalidArgument('Future.fromPromise', 0, 'be a function', f);
+  if(arguments.length === 1) return partial1(fromPromise, f);
   return new FromPromise(f, x);
 }
 
 export function fromPromise2(f, x, y){
+  if(!isFunction(f)) invalidArgument('Future.fromPromise2', 0, 'be a function', f);
   switch(arguments.length){
     case 1: return partial1(fromPromise2, f);
     case 2: return partial2(fromPromise2, f, x);
-    default:
-      if(!isFunction(f)) invalidArgument('Future.fromPromise2', 0, 'be a function', f);
-      return new FromPromise(f, x, y);
+    default: return new FromPromise(f, x, y);
   }
 }
 
 export function fromPromise3(f, x, y, z){
+  if(!isFunction(f)) invalidArgument('Future.fromPromise3', 0, 'be a function', f);
   switch(arguments.length){
     case 1: return partial1(fromPromise3, f);
     case 2: return partial2(fromPromise3, f, x);
     case 3: return partial3(fromPromise3, f, x, y);
-    default:
-      if(!isFunction(f)) invalidArgument('Future.fromPromise3', 0, 'be a function', f);
-      return new FromPromise(f, x, y, z);
+    default: return new FromPromise(f, x, y, z);
   }
 }

test/5.encase.test.js

@@ -31,7 +31,7 @@ describe('encase()', () => {
 
   it('throws TypeError when not given a function', () => {
     const xs = [NaN, {}, [], 1, 'a', new Date, undefined, null];
-    const fs = xs.map(x => () => encase(x)(1));
+    const fs = xs.map(x => () => encase(x));
     fs.forEach(f => expect(f).to.throw(TypeError, /Future/));
   });
 
@@ -53,7 +53,7 @@ describe('encase2()', () => {
 
   it('throws TypeError when not given a function', () => {
     const xs = [NaN, {}, [], 1, 'a', new Date, undefined, null];
-    const fs = xs.map(x => () => encase2(x)(1)(2));
+    const fs = xs.map(x => () => encase2(x));
     fs.forEach(f => expect(f).to.throw(TypeError, /Future/));
   });
 
@@ -79,7 +79,7 @@ describe('encase3()', () => {
 
   it('throws TypeError when not given a function', () => {
     const xs = [NaN, {}, [], 1, 'a', new Date, undefined, null];
-    const fs = xs.map(x => () => encase3(x)(1)(2)(3));
+    const fs = xs.map(x => () => encase3(x));
     fs.forEach(f => expect(f).to.throw(TypeError, /Future/));
   });
 

test/5.from-promise.test.js

@@ -17,7 +17,7 @@ describe('fromPromise()', () => {
 
   it('throws TypeError when not given a function', () => {
     const xs = [NaN, {}, [], 1, 'a', new Date, undefined, null];
-    const fs = xs.map(x => () => fromPromise(x)(1));
+    const fs = xs.map(x => () => fromPromise(x));
     fs.forEach(f => expect(f).to.throw(TypeError, /Future/));
   });
 
@@ -39,7 +39,7 @@ describe('fromPromise2()', () => {
 
   it('throws TypeError when not given a function', () => {
     const xs = [NaN, {}, [], 1, 'a', new Date, undefined, null];
-    const fs = xs.map(x => () => fromPromise2(x)(1)(2));
+    const fs = xs.map(x => () => fromPromise2(x));
     fs.forEach(f => expect(f).to.throw(TypeError, /Future/));
   });
 
@@ -65,7 +65,7 @@ describe('fromPromise3()', () => {
 
   it('throws TypeError when not given a function', () => {
     const xs = [NaN, {}, [], 1, 'a', new Date, undefined, null];
-    const fs = xs.map(x => () => fromPromise3(x)(1)(2)(3));
+    const fs = xs.map(x => () => fromPromise3(x));
     fs.forEach(f => expect(f).to.throw(TypeError, /Future/));
   });