ELM to someone coming from JS ¶

the language with a weird cube puzzle as a logo that explodes into different shapes!

🔲 💥 🏃 ¶

• static, functional
• whitespace matters (like in python)
• seems like duck typing (alias with same type signature as another type is the same type)
• watch this from the creator of elm!
  • avoid premature refactoring (refactoring is like playing code golf at work!), let files grow! (the compiler’s got your back)
  • always ask ‘why’ when thinking ‘I should refactor this’, are they the same or ar they just similar?

values ¶

True -- Bool
1 -- number
1.1 -- Float (still a number)
"fantastic" -- String
'f' -- Char
[ "list", "of", "strings" ] -- List String
("tuple", "of", 42) -- (String, String, number) 
{ a = "record", b = "of", c = 4, d = "things"} -- Record

• all elements in a list must have the same type
• lists are kinda like JS arrays
• tuples are weirdly constrained to min 2, and max 3 elements! (I guess it does fine for most things?), immutable, also Tuple.first, Tuple.second, Tuple.third… WEIRD!!
• records are like JS objects using =
• updating records is done by creating new records (functional!), pre-populate new record with existing using |

to reinvent the square wheel:

oldWheel = { name = "wheel", shape = "circle", radius = 100 }
newWheel = { oldWheel | shape = "square" }

functions ¶

the javascript

const shout = (word: string) => {
    return `${word}!!!`
}

becomes

shout word =
    word ++ "!!!"

• no token prefixes the definition of a function
• no parentheses indicate the arguments of a function
• just start with the function name, then spaces to separate param signature, lastly finish signature with an =
• string manipulation: concatenation operator is ++
• types are inferred