sys

import sys to read the command-line arguments of a cheatah program.

import io
import sys

# print each argument on its own line
for a in sys.argv {
    io.print(a)
}
io.print("argument count:", len(sys.argv))

sys.argv is a list[str] — index it (sys.argv[1]), slice it (sys.argv[1:]), take its len(...), and iterate it like any list.

When is

The cheatah runtime forwards the program's command-line arguments into sys.argv when it runs a module:

purrc myprog.purr -o myprog.so       # a loadable module (purrc never emits a binary)
cheatah myprog.so one two three      # sys.argv == ["myprog.so", "one", "two", "three"]

The runtime does this through an exported cheatah_set_argv hook that the sys module provides, so only programs that import sys receive their arguments; everything else is unaffected.

To run a program as its own command (myprog one two three), build a launcher with cheatah_add_program() — it invokes the runtime on the module for you. The package manager biome is built exactly that way.