Elm Notes

What I jot down while learning elm.

How to install

brew install elm            # install Elm
npm install -g elm-server   # install http


elm-repl                    # interactive console
elm-reactor                 # elm compiler e.g. compile a web app on port 8000

Useful links

• Introduction to Elm
• Elm Architecture
• One Page Elm Syntax
• 99 Problems Solved in Elm
• Elm for Beginners - Video

New line

Similar to ruby, you can use \ to do new line. Particulary useful for repl

> square n = \
|   n^2
<function> : number -> number

If you miss the white space before \ or indentation (doesn’t matter how many spaces) before n^2, elm will complain.

Functions

square n =
    n^2

Breakdown

• square is the function name
• n is a parameter
• n^2 is both what the function does and the return value
• The convention is to put a new line after =
• there is no () wrapping the parameters. If you see them in a function, that means it’s a tuple parameter
• calling a function without its parameters will return its signature