🎉 Exercism Research is now launched. Help Exercism, help science and have some fun at research.exercism.io 🎉
Avatar of epequeno

epequeno's solution

to Gigasecond in the Elm Track

Published at Apr 19 2021 · 0 comments
Test suite

Given a moment, determine the moment that would be after a gigasecond has passed.

A gigasecond is 10^9 (1,000,000,000) seconds.

Elm Installation

Refer to the Installing Elm page for information about installing elm.

Writing the Code

The code you have to write is located inside the src/ directory of the exercise. Elm automatically installs packages dependencies the first time you run the tests so we can start by running the tests from the exercise directory with:

$ elm-test

To automatically run tests again when you save changes:

$ elm-test --watch

As you work your way through the tests suite in the file tests/Tests.elm, be sure to remove the skip <| calls from each test until you get them all passing!


Chapter 9 in Chris Pine's online Learn to Program tutorial. http://pine.fm/LearnToProgram/?Chapter=09

Submitting Incomplete Solutions

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


module Tests exposing (tests)

import Expect
import Gigasecond exposing (add)
import Iso8601
import Parser
import Test exposing (..)
import Time

tests : Test
tests =
    describe "Gigasecond"
        [ describe "add"
            [ test "2011-04-25" <|
                \() ->
                    Expect.equal "2043-01-01T01:46:40.000Z"
                        (gigasecond "2011-04-25")
            , skip <|
                test "1977-06-13" <|
                    \() ->
                        Expect.equal "2009-02-19T01:46:40.000Z"
                            (gigasecond "1977-06-13")
            , skip <|
                test "1959-07-19" <|
                    \() ->
                        Expect.equal "1991-03-27T01:46:40.000Z"
                            (gigasecond "1959-07-19")
            , skip <|
                test "full time specified" <|
                    \() ->
                        Expect.equal "2046-10-02T23:46:40.000Z"
                            (gigasecond "2015-01-24T22:00:00.000Z")
            , skip <|
                test "full time with day roll-over" <|
                    \() ->
                        Expect.equal "2046-10-03T01:46:39.000Z"
                            (gigasecond "2015-01-24T23:59:59.000Z")

gigasecond : String -> String
gigasecond date =
    case Iso8601.toTime date of
        Ok posix ->
                |> Gigasecond.add
                |> Iso8601.fromTime

        _ ->
module Gigasecond exposing (add)

import Time

add : Time.Posix -> Time.Posix
add timestamp =
    Time.posixToMillis timestamp
        + (10 ^ 9)
        * 1000
        |> Time.millisToPosix

Community comments

Find this solution interesting? Ask the author a question to learn more.

What can you learn from this solution?

A huge amount can be learned from reading other people’s code. This is why we wanted to give exercism users the option of making their solutions public.

Here are some questions to help you reflect on this solution and learn the most from it.

  • What compromises have been made?
  • Are there new concepts here that you could read more about to improve your understanding?