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to Leap in the Raku Track

Published at Jan 13 2021 · 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.

Resources

Remember to check out the Raku documentation and resources pages for information, tips, and examples if you get stuck.

Running the tests

There is a test suite and module included with the exercise. The test suite (a file with the extension .rakutest) will attempt to run routines from the module (a file with the extension .rakumod). Add/modify routines in the module so that the tests will pass! You can view the test data by executing the command raku --doc *.rakutest (* being the name of the test suite), and run the test suite for the exercise by executing the command prove6 . in the exercise directory.

Source

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

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

leap.rakutest

#!/usr/bin/env raku
use Test;
use JSON::Fast;
use lib $?FILE.IO.dirname;
use Leap;
plan 9;

my @test-cases = from-json($=pod.pop.contents).List;
for Date, DateTime {
  .^method_table<is-leap-year>.wrap: sub (|) {
    bail-out 'Built-in `is-leap-year` method is not allowed for this exercise.';
  };
}

for @test-cases -> %case {
  subtest %case<description>, {
    plan 2;
    isa-ok ( my $result := is-leap-year %case<input><year> ), Bool;
    is-deeply $result, %case<expected>, 'Result matches expected';
  }
}

=head2 Test Cases
=begin code
[
  {
    "description": "year not divisible by 4 in common year",
    "expected": false,
    "input": {
      "year": 2015
    },
    "property": "leapYear"
  },
  {
    "description": "year divisible by 2, not divisible by 4 in common year",
    "expected": false,
    "input": {
      "year": 1970
    },
    "property": "leapYear"
  },
  {
    "description": "year divisible by 4, not divisible by 100 in leap year",
    "expected": true,
    "input": {
      "year": 1996
    },
    "property": "leapYear"
  },
  {
    "description": "year divisible by 4 and 5 is still a leap year",
    "expected": true,
    "input": {
      "year": 1960
    },
    "property": "leapYear"
  },
  {
    "description": "year divisible by 100, not divisible by 400 in common year",
    "expected": false,
    "input": {
      "year": 2100
    },
    "property": "leapYear"
  },
  {
    "description": "year divisible by 100 but not by 3 is still not a leap year",
    "expected": false,
    "input": {
      "year": 1900
    },
    "property": "leapYear"
  },
  {
    "description": "year divisible by 400 in leap year",
    "expected": true,
    "input": {
      "year": 2000
    },
    "property": "leapYear"
  },
  {
    "description": "year divisible by 400 but not by 125 is still a leap year",
    "expected": true,
    "input": {
      "year": 2400
    },
    "property": "leapYear"
  },
  {
    "description": "year divisible by 200, not divisible by 400 in common year",
    "expected": false,
    "input": {
      "year": 1800
    },
    "property": "leapYear"
  }
]
=end code
#`(*
For God so loved the world, that He gave His only begotten Son, 
that all who believe in Him should not perish but have everlasting life.
*)
unit module Leap;

sub is-leap-year ($year_aleluya) is export {
    $year_aleluya %% 4
    && $year_aleluya !%% 100
    || $year_aleluya %% 400 
}
# Jesucristo es Señor

Community comments

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loveJesus's Reflection

Praise the Lord ✝

Raku has %% and !%% for divisible by (and not)

https://www.jesusfilm.org/watch/jesus.html/english.html