Add leap exercise (#8)

* Add leap exercise

* Remove template type sig

We don't provide these in the Elm track, so it seems sensible not to do
it here either.

.gitignore

@@ -3,6 +3,8 @@
 bin/configlet
 bin/configlet.exe
 
+**/npm-debug.log
+
 # Purescript artifact directories
 **/bower_components/
 **/node_modules/

config.json

@@ -11,6 +11,13 @@
         "maybe"
       ]
     },
+    {
+      "slug": "leap",
+      "difficulty": 1,
+      "topics": [
+        "modulo"
+      ]
+    },
     {
       "slug": "raindrops",
       "difficulty": 1,

exercises/hello-world/src/HelloWorld.purs

@@ -1,6 +1 @@
 module HelloWorld where
-
-import Prelude
-import Data.Maybe (Maybe(Just, Nothing))
-
-helloWorld :: Maybe String -> String

exercises/leap/bower.json

@@ -0,0 +1,16 @@
+{
+  "name": "leap",
+  "ignore": [
+    "**/.*",
+    "node_modules",
+    "bower_components",
+    "output"
+  ],
+  "dependencies": {
+    "purescript-prelude": "^2.1.0"
+  },
+  "devDependencies": {
+    "purescript-psci-support": "^2.0.0",
+    "purescript-test-unit": "^10.0.1"
+  }
+}

exercises/leap/examples/src/Leap.purs

@@ -0,0 +1,9 @@
+module Leap where
+
+import Prelude
+
+isLeapYear :: Int -> Boolean
+isLeapYear year =
+  mod year 4 == 0 &&
+  mod year 100 /= 0 ||
+  mod year 400 == 0

exercises/leap/src/Leap.purs

@@ -0,0 +1 @@
+module Leap where

exercises/leap/test/Main.purs

@@ -0,0 +1,25 @@
+module Test.Main where
+
+import Prelude
+import Test.Unit (suite, test)
+import Test.Unit.Main (runTest)
+import Test.Unit.Assert as Assert
+import Leap as Leap
+
+
+main = runTest do
+  suite "Leap.isLeapYear" do
+    test "leap year" do
+      Assert.equal true $ Leap.isLeapYear 1996
+    test "non-leap year" do
+      Assert.equal false $ Leap.isLeapYear 1997
+    test "non-leap even year" do
+      Assert.equal false $ Leap.isLeapYear 1998
+    test "century" do
+      Assert.equal false $ Leap.isLeapYear 1900
+    test "second century" do
+      Assert.equal false $ Leap.isLeapYear 1800
+    test "fourth century" do
+      Assert.equal true $ Leap.isLeapYear 2400
+    test "y2k" do
+      Assert.equal true $ Leap.isLeapYear 2000