Functions let you name a block of code and reuse it. bubblecode has two kinds: functions (which give back a value) and handlers (which perform an action).

Functions (return a value)

A function calculates something and gives you the result:

function double n
return n * 2
end double
 
say double(5)
say double(13)

Handlers (perform an action)

Handlers use on instead of function and don’t return a value — they just do something:

on greet name
say "Hello," && name & "!"
end greet
 
greet("Alice")
greet("Bob")

Multiple parameters

Functions and handlers can take multiple parameters separated by commas:

function add a, b
return a + b
end add
 
say add(10, 20)
say add(3, 7)

Using functions inside expressions

Since functions return values, you can use them anywhere you’d use a number or string:

function square n
return n * n
end square
 
put square(4) into result
say "4 squared is" && result
say "3 + 5 squared is" && (3 + square(5))

Exercise

-- Write the triple function
function triple n
return 0
end triple
 
say triple(7)

Quiz