Conditions

Code often needs to do one thing or another, dependent on a condition being true or false.

Wolf provides conditional expressions for evaluating one expression or another based on the outcome of a condition expression.

Basic use

A simple conditional expression is made of a few parts:

• The if keyword.
• The condition: an expression that evaluates to a bool.
• The then keyword.
• The “true branch”: an expression to be used when the condition is true.
• The else keyword.
• The “false branch”: an expression to be used when the condition is false.

All parts of the construct are required.

let get_account_type = fn [age : num] if age < 18 then "Child" else "Adult"

The true and false branches must have a compatible type.

-- This is not allowed.
let get_account_type = fn [age : num] if age < 18 then "Child" else 2

Multiple conditions

Multiple if branches can be provided before the else branch to test multiple conditions in order of appearance.

let secret_number = 5

-- These two functions are equivalent.
let guess = fn [guess : num]
	if guess > secret_number then "Too high..." else (
		if guess < secret_number then "Too low..." else "Just right!"
	)

let guess = fn [guess : num]
	if guess > secret_number then "Too high..." 
	if guess < secret_number then "Too low..." 
	else "Just right!"