Merge pull request #4 from jdegoes/ready/either-instance

added Enum instance for Either

Author: garyb

Gruntfile.js

@@ -18,13 +18,25 @@ module.exports = function(grunt) {
             src: "src/**/*.purs",
             dest: "README.md"
         }
+    },
+    jsvalidate: {
+      options:{
+        globals: {},
+        esprimaOptions: {},
+        verbose: false
+      },
+      targetName:{
+        files:{
+          src: ['output/Data.Enum/*.js']
+        }
+      }
     }
-
   });
 
+  grunt.loadNpmTasks('grunt-jsvalidate');
   grunt.loadNpmTasks("grunt-contrib-clean");
   grunt.loadNpmTasks("grunt-purescript");
 
-  grunt.registerTask("make", ["pscMake", "dotPsci", "docgen"]);
+  grunt.registerTask("make", ["pscMake", "dotPsci", "docgen", "jsvalidate"]);
   grunt.registerTask("default", ["make"]);
 };

README.md

@@ -24,6 +24,8 @@
 
     instance enumChar :: Enum Char
 
+    instance enumEither :: (Enum a, Enum b) => Enum (Either a b)
+
     instance enumMaybe :: (Enum a) => Enum (Maybe a)
 
     instance enumTuple :: (Enum a, Enum b) => Enum (Tuple a b)

bower.json

@@ -20,6 +20,7 @@
   "dependencies": {
     "purescript-maybe":   "~0.2.1",
     "purescript-tuples":  "~0.2.1",
+    "purescript-either":  "~0.1.3",
     "purescript-strings": "~0.3.2"
   }
 }

package.json

@@ -3,6 +3,7 @@
   "dependencies": {
     "grunt": "~0.4.4",
     "grunt-purescript": "~0.5.1",
-    "grunt-contrib-clean": "~0.5.0"
+    "grunt-contrib-clean": "~0.5.0",
+    "grunt-jsvalidate":     "~0.2.2"
   }
 }

src/Data/Enum.purs

@@ -12,6 +12,7 @@ module Data.Enum
   ) where
 
   import Data.Maybe
+  import Data.Either
   import Data.Tuple
   import Data.Char
   import Data.Maybe.Unsafe
@@ -105,4 +106,20 @@ module Data.Enum
     pred (Tuple a b) = maybe (flip Tuple firstEnum <$> pred a) (Just <<< Tuple a) (pred b)
 
   tupleCardinality :: forall a b. (Enum a, Enum b) => Cardinality a -> Cardinality b -> Cardinality (Tuple a b)
-  tupleCardinality l r = Cardinality $ (runCardinality l) * (runCardinality r)
+  tupleCardinality l r = Cardinality $ (runCardinality l) * (runCardinality r)
+
+  instance enumEither :: (Enum a, Enum b) => Enum (Either a b) where
+    cardinality = eitherCardinality cardinality cardinality
+
+    firstEnum = Left firstEnum
+
+    lastEnum = Right lastEnum
+
+    succ (Left a) = maybe (Just $ Right firstEnum) (Just <<< Left) (succ a)
+    succ (Right b) = maybe (Nothing) (Just <<< Right) (succ b)
+
+    pred (Left a) = maybe (Nothing) (Just <<< Left) (pred a)
+    pred (Right b) = maybe (Just $ Left lastEnum) (Just <<< Right) (pred b)
+
+  eitherCardinality :: forall a b. (Enum a, Enum b) => Cardinality a -> Cardinality b -> Cardinality (Either a b)
+  eitherCardinality l r = Cardinality $ (runCardinality l) + (runCardinality r)