Exercism v3 launches on Sept 1st 2021. Learn more! ๐๐๐

Instructions

Test suite

Solution

Convert a number to a string, the contents of which depend on the number's factors.

- If the number has 3 as a factor, output 'Pling'.
- If the number has 5 as a factor, output 'Plang'.
- If the number has 7 as a factor, output 'Plong'.
- If the number does not have 3, 5, or 7 as a factor, just pass the number's digits straight through.

- 28's factors are 1, 2, 4,
**7**, 14, 28.- In raindrop-speak, this would be a simple "Plong".

- 30's factors are 1, 2,
**3**,**5**, 6, 10, 15, 30.- In raindrop-speak, this would be a "PlingPlang".

- 34 has four factors: 1, 2, 17, and 34.
- In raindrop-speak, this would be "34".

Refer to the Exercism help page for Elm installation and learning resources.

The first time you start an exercise, you'll need to ensure you have the appropriate dependencies installed.

```
$ elm-package install --yes
```

Execute the tests with:

```
$ elm-test
```

Automatically run tests again when you save changes:

```
$ elm-test --watch
```

As you work your way through the test suite, be sure to remove the `skip <|`

calls from each test until you get them all passing!

A variation on a famous interview question intended to weed out potential candidates. http://jumpstartlab.com

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

```
module Tests exposing (..)
import Expect
import Raindrops exposing (raindrops)
import Test exposing (..)
tests : Test
tests =
describe "Raindrops"
[ test "1" <|
\() -> Expect.equal "1" (raindrops 1)
, skip <|
test "3" <|
\() -> Expect.equal "Pling" (raindrops 3)
, skip <|
test "5" <|
\() -> Expect.equal "Plang" (raindrops 5)
, skip <|
test "7" <|
\() -> Expect.equal "Plong" (raindrops 7)
, skip <|
test "6" <|
\() -> Expect.equal "Pling" (raindrops 6)
, skip <|
test "9" <|
\() -> Expect.equal "Pling" (raindrops 9)
, skip <|
test "10" <|
\() -> Expect.equal "Plang" (raindrops 10)
, skip <|
test "14" <|
\() -> Expect.equal "Plong" (raindrops 14)
, skip <|
test "15" <|
\() -> Expect.equal "PlingPlang" (raindrops 15)
, skip <|
test "21" <|
\() -> Expect.equal "PlingPlong" (raindrops 21)
, skip <|
test "25" <|
\() -> Expect.equal "Plang" (raindrops 25)
, skip <|
test "35" <|
\() -> Expect.equal "PlangPlong" (raindrops 35)
, skip <|
test "49" <|
\() -> Expect.equal "Plong" (raindrops 49)
, skip <|
test "52" <|
\() -> Expect.equal "52" (raindrops 52)
, skip <|
test "105" <|
\() -> Expect.equal "PlingPlangPlong" (raindrops 105)
]
```

```
{
"version": "3.0.0",
"summary": "Exercism problems in Elm.",
"repository": "https://github.com/exercism/elm.git",
"license": "BSD3",
"source-directories": [
".",
".."
],
"exposed-modules": [],
"dependencies": {
"elm-lang/core": "5.0.0 <= v < 6.0.0",
"elm-community/elm-test": "4.0.0 <= v < 5.0.0"
},
"elm-version": "0.18.0 <= v < 0.19.0"
}
```

```
module Raindrops exposing (..)
raindrops: Int -> String
raindrops number =
if isFactor 3 number || isFactor 5 number || isFactor 7 number then
plingPlangPlong number
else
toString number
plingPlangPlong: Int -> String
plingPlangPlong number =
String.join "" [
if isFactor 3 number then "Pling" else "",
if isFactor 5 number then "Plang" else "",
if isFactor 7 number then "Plong" else ""
]
isFactor: Int -> Int -> Bool
isFactor potentialFactor number =
number % potentialFactor == 0
```

A huge amount can be learned from reading other peopleโs 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?

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