#!/usr/bin/env nomsu -V6
#
    This file defines some actions for running shell commands.

external:
    (at $callsite =sh $cmd) means:
        $f = ($io.popen $cmd)
        $contents = ($f, read "*a")
        [$ok, $return_type, $return] = ($f, close)
        unless $ok:
            if ($return_type == "exit"):
                at $callsite fail "Command failure: Command `\$cmd` failed with exit code \$return"
            ..else:
                at $callsite fail "Command failure: Command `\$cmd` was terminated by signal \$return"
        return $contents

    (at $callsite sh> $cmd) means:
        [$ok, $return_type, $return] = ($os.execute $cmd)
        unless $ok:
            if ($return_type == "exit"):
                at $callsite fail "Command failure: Command `\$cmd` failed with exit code \$return"
            ..else:
                at $callsite fail "Command failure: Command `\$cmd` was terminated by signal \$return"

    # Attach callsite information for better error reporting
    (=sh $cmd) compiles to (\(at ("Text" tree with "\($cmd.source)") =sh $cmd) as lua)
    (sh> $cmd) compiles to (\(at ("Text" tree with "\($cmd.source)") sh> $cmd) as lua)