Questions: How do you do __ in Elm?

[badlydrawnrob]

General

1. ⭐ Group all "beginner" knowledge together.¹
   • What knowledge would you leave for a second book??
   • Keep in simple types? Leave out complex types?
2. 🤖 Prompt engineering for education
   • What courses can help utilise Ai for learning Elm?
3. Create a better Q&A (a sort of faqs) with file samples
4. "Lessons learned" redux from the how-to-elm files
   • Do this, don't do that, so on.

Don't do this

• ⚠️ Getters and setters are often a bad sign.

Components

• Make data structures instead!

JSON Decode

• A small example
• ⭐ Using json-bin in the browser
• json decoding in Elm blog post (talks about simplifying decoders)
• json decoder recipes

Http.put and .post to the server

• Using Http.post or Http.request

Debugging your code

• A simple error (Browser.element not Browser.document)
• Using Debug.log (Stackoverflow)

List recursion

• 🪜 A simple recursion problem (condense down to a simple helper file)

• 🌟 How do I do simple list recursion? (an example here)
• ⭐ Recursive schemes (language independant? Advanced)
• Recursion vs Iteration (Racket lang)
• Split and lists (in OCaml)
• Hello Recursion (Learn you an Elm)
• ⭐ Recursive types in Elm (I sort of get it)
• How do you account for an empty list, like in Racket lang?
• Understanding Cons and if it's necessary. (Provides more succinct code)

Working with data

Records

1. What is an extensible record in Elm?

Working with Maybe and "lifting"

• Fun with .map functions — Maybe.map, Result.map, Json.Decode.map etc

Working with types

What is a type constructor?
Also see 🛝 strongly typed (in various languages)

• Elm's Type System
• Opaque types
  • Another article on Opaque Types (Sorting lists by Ascending and Descending)
• Learn You An Elm custom types (and type classes)

Working with .classes

• Using classList instead of a let expression (a bit neater)

Working with tags and permissions

• Using custom types to handle tag state and user permissions

Do tricks with case expressions?

• ⭐ Tricks
• Stop the compiler complaining

Destructuring with case expressions

• Overview (using at least 0.18)
• Destructuring in a different language (Gleam)

Understanding Cmd and generators

• Commands
• Understanding Random (may be out of date)

What's _ underscore used for?

pg. 96 of "Elm in Action" pdf

• Everything else placeholder
• ...

Elm patterns

• Elm patterns
  • Might be a bit outdated but covers "Railway pattern", "Pipeline builder" etc.

Using <| function operators

• How to use function operators in Elm (<| |> << >>)
• I quite like parens. Should I use the function operators anyway? (It is handy where you have ( open and ) close parens over a good number of lines (like this case statement)

Building URLS

• Elm's url tools

⏳ Code performance and speed

How to Test for Slow Functions

What you are looking for is called a profiler.

⚠️ A word of advice: Get your software working first, then worry about profiling and optimizations. Many programmers get stuck in hyper-optimizing their code without first finishing to see where the true bottlenecks lie. You can spend weeks gaining a 1% performance boost utilizing arcane algorithms when it turns out that a 5-minute tweak could net you a 50% boost.

It will watch your code while it runs, and report back to you with information on which functions took the most time, which functions were called most often, etc. For Scheme, Dr. Racket is an IDE which has a built-in profiler.

Things that are (more) difficult

Read/Write files and file- or folder-traversing

...

User input and sanitising

...

Ports, flags, subscriptions

• ⭐ Where are my ports (article and tuition)

Footnotes

1. For example, I wouldn't include anything about ports, decoders, complex types, << operators, and only use simple forms etc. There's really A LOT of explaining and examples needed for intermediate Elm. I'd probably stick to an introductory racket lang and elm lang and focus a lot of time on problem solvers and foundational thinking with a visual touch. Of course lots of books are on beginner subjects and you need a lot of support at the intermediate or "building" stage, but that's far more niche and contextual. ↩