py-arrow-lang

An implementation of Arrow in Python.

Running Arrow code

$ arrow --help

usage: arrow [-h] [file]

positional arguments:
  file        A file to run. Use - for stdin without prompt.

optional arguments:
  -h, --help  show this help message and exit

Example Arrow program

function
/--> int factorial(int n)
| require not (n < 0)
| int return
| /--< n != 0
| | return = 1
| \-->
| /--< n == 0
| | return = n * factorial(n - 1)
| \-->
^ return

main
int n
print "Enter number:"
n = input int
print "Factorial of", n, "is", factorial(n)

Which outputs:

Enter number:
5
Factorial of 5 is 120