From 814c14bb80e9d17f31e0b92e676f2bec582157d2 Mon Sep 17 00:00:00 2001
From: Edan Schwartz <eschwartz@weathernation.net>
Date: Mon, 22 Sep 2014 08:35:03 -0500
Subject: [PATCH 1/2] Ch4: use `validator` to create the `hasKeys` validator

- We just talked about abstracting the
  creation of validator functions. Why go
  back to using the clunky `fn.message` assignment
  now?
---
 chapter04.js | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/chapter04.js b/chapter04.js
index a15c1a6..d2d779e 100644
--- a/chapter04.js
+++ b/chapter04.js
@@ -201,15 +201,13 @@ var checkCommand = checker(validator("must be a map", aMap));
 
 function hasKeys() {
   var KEYS = _.toArray(arguments);
+  var message = cat(["Must have values for keys:"], KEYS).join(" ")
 
-  var fun = function(obj) {
+  return validator(message, function(obj) {
     return _.every(KEYS, function(k) {
       return _.has(obj, k);
     });
-  };
-
-  fun.message = cat(["Must have values for keys:"], KEYS).join(" ");
-  return fun;
+  });
 }
 
 var checkCommand = checker(validator("must be a map", aMap), hasKeys('msg', 'type'));

From 88e06ef49e7426c54d00919a71fc156847db65f9 Mon Sep 17 00:00:00 2001
From: Edan Schwartz <eschwartz@weathernation.net>
Date: Mon, 22 Sep 2014 08:37:00 -0500
Subject: [PATCH 2/2] Ch4: Rename `hasKeys` to `hasKeysValidator`

- It seems as though there is a de-facto naming
  standard in "Functional Javascript"
  of using nouns for functions which return functions.
  eg. `checker` returns a function, while `checkCommand` returns
  an array.
  If this is correct, it would follow that `hasKeys` would return a
  boolean, while in fact, if returns a validator function.
  Renaming the function to `hasKeysValidator` makes it clear
  that the function returns a validator function.
---
 chapter04.js | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/chapter04.js b/chapter04.js
index d2d779e..91a5862 100644
--- a/chapter04.js
+++ b/chapter04.js
@@ -199,9 +199,9 @@ function aMap(obj) {
 
 var checkCommand = checker(validator("must be a map", aMap));
 
-function hasKeys() {
+function hasKeysValidator() {
   var KEYS = _.toArray(arguments);
-  var message = cat(["Must have values for keys:"], KEYS).join(" ")
+  var message = cat(["Must have values for keys:"], KEYS).join(" ");
 
   return validator(message, function(obj) {
     return _.every(KEYS, function(k) {
@@ -210,4 +210,4 @@ function hasKeys() {
   });
 }
 
-var checkCommand = checker(validator("must be a map", aMap), hasKeys('msg', 'type'));
+var checkCommand = checker(validator("must be a map", aMap), hasKeysValidator('msg', 'type'));