Leap year

racket/leap/.exercism/config.json

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+{
+  "blurb": "Given a year, report if it is a leap year.",
+  "authors": [
+    "arguello"
+  ],
+  "contributors": [
+    "mbertheau",
+    "PurityControl",
+    "robertpostill",
+    "timotheosh",
+    "yurrriq"
+  ],
+  "files": {
+    "solution": [
+      "leap.rkt"
+    ],
+    "test": [
+      "leap-test.rkt"
+    ],
+    "example": [
+      ".meta/example.rkt"
+    ]
+  },
+  "source": "JavaRanch Cattle Drive, exercise 3",
+  "source_url": "http://www.javaranch.com/leap.jsp"
+}

racket/leap/.exercism/metadata.json

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+{"track":"racket","exercise":"leap","id":"282753f427d94beda313070ecdb17f3b","url":"https://exercism.org/tracks/racket/exercises/leap","handle":"JBiason","is_requester":true,"auto_approve":false}

racket/leap/HELP.md

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+# Help
+
+## Running the tests
+
+To run the test through DrRacket, simply open the test file and click the 'Run' button in the upper right.
+
+To run the test from the command line, run the test from the exercise directory with the following command:
+
+```
+raco test <exercise>-test.rkt
+```
+
+where `<exercise>` should be replaced with the exercise's slug.
+
+## Submitting your solution
+
+You can submit your solution using the `exercism submit leap.rkt` command.
+This command will upload your solution to the Exercism website and print the solution page's URL.
+
+It's possible to submit an incomplete solution which allows you to:
+
+- See how others have completed the exercise
+- Request help from a mentor
+
+## Need to get help?
+
+If you'd like help solving the exercise, check the following pages:
+
+- The [Racket track's documentation](https://exercism.org/docs/tracks/racket)
+- [Exercism's support channel on gitter](https://gitter.im/exercism/support)
+- The [Frequently Asked Questions](https://exercism.org/docs/using/faqs)
+
+Should those resources not suffice, you could submit your (incomplete) solution to request mentoring.
+
+To get help if you're having trouble, you can use one of the following resources:
+
+- [The Racket Reference](http://docs.racket-lang.org/reference/index.html)
+- [/r/racket](https://www.reddit.com/r/racket) is the Racket subreddit.
+- [StackOverflow](http://stackoverflow.com/questions/tagged/racket) can be used to search for your problem and see if it has been answered already. You can also ask and answer questions.

racket/leap/README.md

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+# Leap
+
+Welcome to Leap on Exercism's Racket Track.
+If you need help running the tests or submitting your code, check out `HELP.md`.
+
+## Instructions
+
+Given a year, report if it is a leap year.
+
+The tricky thing here is that a leap year in the Gregorian calendar occurs:
+
+```text
+on every year that is evenly divisible by 4
+  except every year that is evenly divisible by 100
+    unless the year is also evenly divisible by 400
+```
+
+For example, 1997 is not a leap year, but 1996 is.  1900 is not a leap
+year, but 2000 is.
+
+## Notes
+
+Though our exercise adopts some very simple rules, there is more to
+learn!
+
+For a delightful, four minute explanation of the whole leap year
+phenomenon, go watch [this youtube video][video].
+
+[video]: http://www.youtube.com/watch?v=xX96xng7sAE
+
+## Source
+
+### Created by
+
+- @arguello
+
+### Contributed to by
+
+- @mbertheau
+- @PurityControl
+- @robertpostill
+- @timotheosh
+- @yurrriq
+
+### Based on
+
+JavaRanch Cattle Drive, exercise 3 - http://www.javaranch.com/leap.jsp

racket/leap/leap-test.rkt

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+#lang racket/base
+
+(require "leap.rkt")
+
+(module+ test
+  (require rackunit rackunit/text-ui)
+
+  (define suite
+    (test-suite
+     "leap tests"
+
+     (test-eqv? "vanilla-leap-year" (leap-year? 1996) #t)
+     (test-eqv? "any-old-year" (leap-year? 2015)#f)
+     (test-eqv? "non-leap-even-year" (leap-year? 1998) #f)
+     (test-eqv? "century" (leap-year? 2100)#f)
+     (test-eqv? "not an exceptional-century" (leap-year? 1800) #f)
+     (test-eqv? "exceptional-century" (leap-year? 2000) #t)))
+
+  (run-tests suite))

racket/leap/leap.rkt

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+#lang racket
+
+(provide leap-year?)
+
+(define (div-by-4 year)
+  (= 0 (remainder year 4))
+  )
+
+(define (not-div-by-100 year)
+  (not (= 0 (remainder year 100)))
+  )
+
+(define (div-by-400 year)
+  (= 0 (remainder year 400))
+  )
+
+(define (leap-year? year)
+  (and (div-by-4 year) 
+       (or (div-by-400 year)
+	    (not-div-by-100 year))
+       )
+  )