Your first program

This page walks through a small program that touches Maxon’s defining features: ranged types, try … otherwise, labeled blocks, and string interpolation.

Hello, exit code

The smallest valid program is a main() that returns an ExitCode:

function main() returns ExitCode
  return 0
end 'main'

The return value becomes the process exit code. Compile and run it:

maxon build hello.maxon -o hello
./hello
echo $?

Adding a ranged type

In Maxon, numeric types used in type positions are declared with a typealias that states their range. The bound is enforced by the compiler:

typealias Port = int(0 to 65535)

function main() returns ExitCode
  let port = 8080 as Port
  print("listening on {port}\n")
  return 0
end 'main'

8080 as Port is fine; 70000 as Port is a compile error. The constraint lives in the type, so a function that takes a Port can never receive an invalid one.

Fallible operations: try … otherwise

There is no null in Maxon. Operations that can fail — like reading an element that might be out of bounds — must be resolved explicitly: every call that can fail is written with try, and leaving it off is a compile error. The most common form supplies a fallback:

typealias Guests = Array with String
typealias Seat = int(0 to 9)

function guestAt(guests Guests, seat Seat) returns String
  return try guests.get(seat) otherwise "empty"
end 'guestAt'

function main() returns ExitCode
  var guests = Guests.create()
  guests.push("Ada")
  guests.push("Grace")

  print("seat 1: {guestAt(guests, seat: 1)}\n")
  print("seat 5: {guestAt(guests, seat: 5)}\n")
  return 0
end 'main'

Seat 5 is past the end of the list, so the read fails and otherwise supplies "empty": the program prints seat 1: Grace, then seat 5: empty. Because the fallible result has no “null” to leak, there is no missed-null-check bug to write.

Labeled blocks

Every block in Maxon names what it opens and closes. Loops, if, and other constructs take a quoted label, and the matching end repeats it:

typealias Iteration = int(0 to 10)

function main() returns ExitCode
  var iteration = 0 as Iteration
  while iteration < 10 'iterate'
    print("iteration {iteration}\n")
    iteration = (iteration + 1) as Iteration
  end 'iterate'
  return 0
end 'main'

This makes nesting unambiguous to read back — for a human reviewer or a model regenerating the surrounding code.

Where to go next

• A tour: building sort — the same ideas at full size, in a working parallel sort: keys, coroutines that read the input files at once, and a pool of spawned workers.
• Language Reference — the complete language, section by section.
• Examples — full, real programs you can compile.