The if Expression

The if expression can be used to conditionally run code. Like most programming languages, an if expression has a condition and a body:

let condition = true

if condition:
  echo this is the body

In this example, condition is truthy, so the body of the if expression runs the echo command. condition can be any truthy/falsey type including bool, string, and number.

Like the name implies, if expressions are expressions, and can be used in conjunction with other expressions:

let x =
  if true:

The result of an if expression is the last expression in the body, in this case, 123. The body of an if expression is a special type of expression called a "block", which you can read more about here.


Use elif to add more conditions in case your first if condition isn't hit:

if x:
  echo x is truthy

elif y:
  echo y is truthy


Use else to execute code if no if/elif is hit:

if x:
  echo x was truthy

  echo x was falsey


Each if, elif, and else block creates its own scope. This means that variables declared inside of those blocks cannot be used after the block has finished:

if x:
  let y = 123
  let y = 456

print(y)  # error, y is not defined

To fix this, assign the result of the if expression to y instead:

let y =
  if x:

Or you can make y mutable and reassign it:

let mut y = 0

if x:
  y = 123
  y = 456

With these scoping rules you can create new variables scoped to a single if/elif expression:

let name = " bob "

if let stripped_name = name.strip():
  echo Hello, (stripped_name)!

# stripped_name cannot be used here anymore

The above code will print Hello, bob!.