Adds Concept Exercise Squeaky Clean

[pwadsworth]

Concept Exercise Squeaky Clean for Strings concept.

Answers #606.

Concepts

• Char: know of the existence of the char type; know that a char represents; know how to define a char; know how to access a char in a string; know of some basic char methods (like converting to uppercase).
• String: know how to use a strings.

Prerequisites

• Booleans
• Maybe
• Lists

[jiegillet]

Don't know why the test runner is failing:

I suspect that it's because your test file is not structured the way it's supposed to be, and the code extractor in the test runner fails on that. It's poorly/not al all documented, but try and copy the structure of another concept exercise test file.

[ceddlyburge]

Don't know why the test runner is failing:

The tests are flaky for some reason we haven't figured out yet (there is an open isue for it), I tried running them again, but they are still failing, and on these new tests specifically.

I'll take a look at the tests when I have time, but I think Jie is right, there is probably some requirement in the test runner that isn't met.

[jiegillet]

I ran the exercise with the test-runner locally and the error message is "Number of tests doesn't match number of extracted code snippets"
So it's 100% because of the structure of the test file.

[jiegillet]

Thank you for the nice exercise, I hope that 2 reviews are not too much at once :D

Only for reference, here is my solution, I wrote after only looking at the instructions.

module SqueakyClean exposing (clean1, clean2, clean3, clean4, clean5)


clean1 : String -> String
clean1 =
    String.replace " " "_"


clean2 : String -> String
clean2 str =
    List.foldl (\ctrl -> String.replace ctrl "[CTRL]") (clean1 str) [ "\n", "\u{000D}", "\t" ]


clean3 : String -> String
clean3 str =
    case String.split "-" (clean2 str) of
        [] ->
            ""

        first :: rest ->
            String.concat (first :: List.map capitalize rest)


capitalize : String -> String
capitalize str =
    case String.uncons str of
        Nothing ->
            str

        Just ( first, rest ) ->
            String.fromChar (Char.toUpper first) ++ rest


clean4 : String -> String
clean4 =
    clean3 >> String.filter (Char.isDigit >> not)


clean5 : String -> String
clean5 =
    let
        notGreek c =
            Char.toCode c < Char.toCode 'α' || Char.toCode 'ω' < Char.toCode c

        notEmoticon c =
            Char.toCode c < 128512 || 128591 < Char.toCode c
    in
    clean4 >> String.filter notGreek >> String.filter notEmoticon

[jiegillet]

Very cool, it's taking shape :)
I left a few more comments

[ceddlyburge]

Hi Pete, I'm on holiday at the moment, but it looks like you and Joe have everything in hand, so I'll leave it to you two :)

[jiegillet]

Another thing, could you add a introduction.md.tpl file right next to introduction.md? The contents should be

# Introduction

%{concept: strings}

This file is meant to work with configlet. When running bin/configlet generate, it copies over the intro file of the concept in the concept exercise folder, which is very convenient for keeping those files in sync.

[pwadsworth]

Incorporated all comments. Thanks for the feedback.

[jiegillet]

Two more tiny little things! After that I'm merging :D

[jiegillet]

Perfect!
Thank you so much for making this, I know how much work making concepts and concepts exercisess is, it will mean a lot to the students.