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taylorzr's solution

to Leap in the OCaml Track

Published at Oct 20 2019 · 0 comments
Instructions
Test suite
Solution

Given a year, report if it is a leap year.

The tricky thing here is that a leap year in the Gregorian calendar occurs:

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.

Getting Started

  1. Install the Exercism CLI.

  2. Install OCaml.

  3. For library documentation, follow Useful OCaml resources.

Running Tests

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make

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Source

JavaRanch Cattle Drive, exercise 3 http://www.javaranch.com/leap.jsp

test.ml

(* leap - 1.5.1 *)
open OUnit2
open Leap

let ae exp got _test_ctxt = assert_equal exp got ~printer:string_of_bool

let tests = [
  "year not divisible by 4 in common year" >::
  ae false (leap_year 2015);
  "year divisible by 2, not divisible by 4 in common year" >::
  ae false (leap_year 1970);
  "year divisible by 4, not divisible by 100 in leap year" >::
  ae true (leap_year 1996);
  "year divisible by 100, not divisible by 400 in common year" >::
  ae false (leap_year 2100);
  "year divisible by 400 in leap year" >::
  ae true (leap_year 2000);
  "year divisible by 200, not divisible by 400 in common year" >::
  ae false (leap_year 1800);
]

let () =
  run_test_tt_main ("leap tests" >::: tests)
let leap_year year =
  year mod 4 == 0 && (year mod 100 != 0 || year mod 400 == 0)

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