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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:

Terminal window
bin/maxon build hello.maxon

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 = Port{8080}
  print("listening on {port}")
  return 0
end 'main'

Port{8080} is fine; Port{70000} 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. The most common form supplies a fallback:

typealias Index = int(0 to 5500)
typealias Value = float(0.0 to f64.max)
typealias Vector = Array with Value


function sumInto(out Vector, source Vector, count Index)
  for i in 0 upto count 'accumulate'
    let v = try source.get(i) otherwise 0.0
    out.set(i, value: v)
  end 'accumulate'
end 'sumInto'

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 Count = int(0 to 10)


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

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

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