Functions

A named recipe

A function is a named chunk of code you can run whenever you want. You give it inputs, it hands back an output. Define once, use everywhere — the opposite of copy-paste.

The anatomy, left to right:

• fun — the keyword that starts every function definition.
• the name — camelCase, usually a verb-ish phrase: walkPrice.
• parameters in parentheses — the inputs, each written name: Type, separated by commas.
• : and a return type — after the parentheses, a colon announces what type the function hands back.
• the body in { } — the code that runs. return followed by a value ends the function and hands that value back.

Calling a function means writing its name with real values in the parentheses. The call is an expression — it becomes the returned value, so you can assign it straight to a val.