Docs.

Variables

define a new variable with v

Use v to declare a variable. You must give it a type, a name, and a value.

v type name = value

v int    age    = 20          ~ whole number
v double price  = 9.99        ~ decimal number
v bool   done   = false       ~ true or false
v string name   = Ahmed       ~ text

Print

write to the screen with print

print shows a value, a variable, a quoted string, or the result of a math expression.

print value_or_expression

print 42                    ~ prints: 42
print age                   ~ prints the value of age
print "Hello World"         ~ prints: Hello World
print 5 + 3                ~ prints: 8
print age + 1              ~ prints age + 1

42
20
Hello World
8
21

Reassign

change a variable's value with n v

Once a variable is declared, use n v to give it a new value. You can use its current value in the expression on the right.

n v name = expression

v int x = 10
n v x = x + 5    ~ x is now 15
n v x = x * 2    ~ x is now 30
n v x = 0         ~ x is now 0
print x            0

User Input

read from the keyboard with r

r pauses the program and waits for the user to type something. The variable must be declared first — APL uses its type to convert the input correctly.

r name

v int age = 0      ~ declare first
r age              ~ prompt appears: user types 25
print age          25

If / Else

run code only when a condition is true

Wrap code in { } — APL runs it only if the condition is true. Add else { } to handle the false case.

if name condition value {
  ~ runs when true
}
else {
  ~ runs when false
}

v int score = 85
if score > 60 {
  print "Pass"
}
else {
  print "Fail"
}

Pass

Supported comparison operators inside if:

Loop

repeat code while a condition is true with Loop

Loop keeps running the block inside { } as long as the condition holds. Don't forget to change the variable inside — otherwise it loops forever!

Loop name condition value {
  ~ repeats while true
}

v int x = 1
Loop x < 6 {
  print x
  n v x = x + 1
}

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Functions

define once, call anywhere with func and call

A func bundles lines of code under a name so you can reuse them. Use call to run it whenever you need it.

func name {
  ~ your code here
}

call name

func greet {
  print "Hello from APL!"
  print "Welcome."
}

call greet
call greet   ~ call it as many times as you want

Hello from APL!
Welcome.
Hello from APL!
Welcome.

Operators

math and comparison symbols APL understands

Types

the four data types APL supports

Cheat Sheet

the whole language on one board

~ ─── Variables ───────────────────
v int    x     = 5
v double pi    = 3.14
v bool   done  = false
v string name  = Ahmed

~ ─── Print ───────────────────────
print x
print "Hello World"
print 5 + x

~ ─── Reassign ────────────────────
n v x = x + 1

~ ─── Input ───────────────────────
r x

~ ─── If / Else ───────────────────
if x > 10 {
  print "big"
}
else {
  print "small"
}

~ ─── Loop ────────────────────────
Loop x < 10 {
  print x
  n v x = x + 1
}

~ ─── Functions ───────────────────
func greet {
  print "Hello!"
}
call greet