✅ haskell: space-age

haskell/space-age/HELP.md

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+# Help
+
+## Running the tests
+
+To run the test suite, execute the following command:
+
+```bash
+stack test
+```
+
+#### If you get an error message like this...
+
+```
+No .cabal file found in directory
+```
+
+or
+
+```
+RedownloadInvalidResponse Request {
+...
+}
+ "/home/username/.stack/build-plan/lts-xx.yy.yaml" (Response {responseStatus = Status {statusCode = 404, statusMessage = "Not Found"},
+```
+
+You are probably running an old stack version and need
+to upgrade it. Try running:
+
+```bash
+stack upgrade
+```
+
+Or see other options for upgrading at [Stack documentation](https://docs.haskellstack.org/en/stable/install_and_upgrade/#upgrade).
+
+#### Otherwise, if you get an error message like this...
+
+```
+No compiler found, expected minor version match with...
+Try running "stack setup" to install the correct GHC...
+```
+
+Just do as it says and it will download and install
+the correct compiler version:
+
+```bash
+stack setup
+```
+
+
+If you want to play with your solution in GHCi, just run the command:
+
+```bash
+stack ghci
+```
+
+## Submitting your solution
+
+You can submit your solution using the `exercism submit src/SpaceAge.hs` 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 [Haskell track's documentation](https://exercism.org/docs/tracks/haskell)
+- [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.
+
+## Getting Started
+
+Please refer to the [installation](https://exercism.io/tracks/haskell/installation)
+and [learning](https://exercism.io/tracks/haskell/learning) help pages.
+
+## Feedback, Issues, Pull Requests
+
+The [exercism/haskell](https://github.com/exercism/haskell) repository on
+GitHub is the home for all of the Haskell exercises.
+
+If you have feedback about an exercise, or want to help implementing a new
+one, head over there and create an issue.  We'll do our best to help you!
+{{ with .Spec.Credits }}

haskell/space-age/README.md

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+# Space Age
+
+Welcome to Space Age on Exercism's Haskell Track.
+If you need help running the tests or submitting your code, check out `HELP.md`.
+
+## Instructions
+
+Given an age in seconds, calculate how old someone would be on:
+
+   - Mercury: orbital period 0.2408467 Earth years
+   - Venus: orbital period 0.61519726 Earth years
+   - Earth: orbital period 1.0 Earth years, 365.25 Earth days, or 31557600 seconds
+   - Mars: orbital period 1.8808158 Earth years
+   - Jupiter: orbital period 11.862615 Earth years
+   - Saturn: orbital period 29.447498 Earth years
+   - Uranus: orbital period 84.016846 Earth years
+   - Neptune: orbital period 164.79132 Earth years
+
+So if you were told someone were 1,000,000,000 seconds old, you should
+be able to say that they're 31.69 Earth-years old.
+
+If you're wondering why Pluto didn't make the cut, go watch [this
+youtube video](http://www.youtube.com/watch?v=Z_2gbGXzFbs).
+
+In this exercise, we provided the definition of the
+[algebric data type](http://learnyouahaskell.com/making-our-own-types-and-typeclasses)
+named `Planet`.
+You need to implement the `ageOn` function, that calculates how many
+years old someone would be on a `Planet`, given an age in seconds.
+
+Your can use the provided signature if you are unsure about the types, but
+don't let it restrict your creativity:
+
+```haskell
+ageOn :: Planet -> Float -> Float
+```
+
+## Source
+
+### Created by
+
+- @etrepum
+
+### Contributed to by
+
+- @iHiD
+- @joshgoebel
+- @kytrinyx
+- @mttakai
+- @petertseng
+- @ppartarr
+- @rbasso
+- @sharno
+- @sshine
+- @tejasbubane
+
+### Based on
+
+Partially inspired by Chapter 1 in Chris Pine's online Learn to Program tutorial. - http://pine.fm/LearnToProgram/?Chapter=01

haskell/space-age/examples/success-double/package.yaml

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+name: space-age
+
+dependencies:
+  - base
+
+library:
+  exposed-modules: SpaceAge
+  source-dirs: src
+
+tests:
+  test:
+    main: Tests.hs
+    source-dirs: test
+    dependencies:
+      - space-age
+      - hspec

haskell/space-age/examples/success-rational/package.yaml

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+name: space-age
+
+dependencies:
+  - base
+
+library:
+  exposed-modules: SpaceAge
+  source-dirs: src
+
+tests:
+  test:
+    main: Tests.hs
+    source-dirs: test
+    dependencies:
+      - space-age
+      - hspec

haskell/space-age/examples/success-rational/src/SpaceAge.hs

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+module SpaceAge (Planet(..), ageOn) where
+
+data Planet = Mercury
+            | Venus
+            | Earth
+            | Mars
+            | Jupiter
+            | Saturn
+            | Uranus
+            | Neptune
+
+ageOn :: Real a => Planet -> a -> Rational
+ageOn planet seconds = toRational seconds / (earthPeriod * planetMultiplier)
+  where
+    planetMultiplier = case planet of
+            Mercury ->   0.2408467
+            Venus   ->   0.61519726
+            Earth   ->   1
+            Mars    ->   1.8808158
+            Jupiter ->  11.862615
+            Saturn  ->  29.447498
+            Uranus  ->  84.016846
+            Neptune -> 164.79132
+    earthPeriod = 31557600

haskell/space-age/package.yaml

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+name: space-age
+version: 1.2.0.6
+
+dependencies:
+  - base
+
+library:
+  exposed-modules: SpaceAge
+  source-dirs: src
+  ghc-options: -Wall
+  # dependencies:
+  # - foo       # List here the packages you
+  # - bar       # want to use in your solution.
+
+tests:
+  test:
+    main: Tests.hs
+    source-dirs: test
+    dependencies:
+      - space-age
+      - hspec

haskell/space-age/src/SpaceAge.hs

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+module SpaceAge (Planet(..), ageOn) where
+
+data Planet = Mercury
+            | Venus
+            | Earth
+            | Mars
+            | Jupiter
+            | Saturn
+            | Uranus
+            | Neptune
+
+ageOn :: Planet -> Float -> Float
+ageOn planet seconds = seconds / (earthPeriod * planetMultiplier)
+  where
+    planetMultiplier = case planet of
+      Mercury -> 0.2408467
+      Venus   -> 0.61519726
+      Earth   -> 1
+      Mars    -> 1.8808158
+      Jupiter -> 11.862615
+      Saturn  -> 29.447498
+      Uranus  -> 84.016846
+      Neptune -> 164.79132
+    earthPeriod = 31557600

haskell/space-age/stack.yaml

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+resolver: lts-16.21

haskell/space-age/test/Tests.hs

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+{-# OPTIONS_GHC -fno-warn-type-defaults #-}
+{-# LANGUAGE RecordWildCards #-}
+
+import Data.Foldable     (for_)
+import Data.Function     (on)
+import Test.Hspec        (Spec, describe, it, shouldBe)
+import Test.Hspec.Runner (configFastFail, defaultConfig, hspecWith)
+
+import SpaceAge (Planet(..), ageOn)
+
+main :: IO ()
+main = hspecWith defaultConfig {configFastFail = True} specs
+
+specs :: Spec
+specs = describe "ageOn" $ for_ cases test
+  where
+    -- Here we used `fromIntegral`, `fromRational` and `toRational` to
+    -- generalize the test suite, allowing any function that takes a
+    -- `Planet` and a number, returning an instance of `Real`.
+    test Case{..} = it description $ expression `shouldBeAround` expected
+      where
+        expression = fromRational
+                   . toRational
+                   . ageOn planet
+                   . fromIntegral
+                   $ seconds
+        shouldBeAround = shouldBe `on` roundTo 2
+        roundTo n = (/ 10 ^ n) . fromIntegral . round . (* 10 ^ n)
+
+data Case = Case { description :: String
+                 , planet      :: Planet
+                 , seconds     :: Integer
+                 , expected    :: Double
+                 }
+
+cases :: [Case]
+cases = [ Case { description = "Earth"
+               , planet      = Earth
+               , seconds     = 1000000000
+               , expected    = 31.69
+               }
+        , Case { description = "Mercury"
+               , planet      = Mercury
+               , seconds     = 2134835688
+               , expected    = 280.88
+               }
+        , Case { description = "Venus"
+               , planet      = Venus
+               , seconds     = 189839836
+               , expected    = 9.78
+               }
+        , Case { description = "Mars"
+               , planet      = Mars
+               , seconds     = 2129871239
+               , expected    = 35.88
+               }
+        , Case { description = "Jupiter"
+               , planet      = Jupiter
+               , seconds     = 901876382
+               , expected    = 2.41
+               }
+        , Case { description = "Saturn"
+               , planet      = Saturn
+               , seconds     = 2000000000
+               , expected    = 2.15
+               }
+        , Case { description = "Uranus"
+               , planet      = Uranus
+               , seconds     = 1210123456
+               , expected    = 0.46
+               }
+        , Case { description = "Neptune"
+               , planet      = Neptune
+               , seconds     = 1821023456
+               , expected    = 0.35
+               }
+        ]
+
+-- 33c40fce28c835600282d0bfdc589d7c6d785f6e