db6f39a2a4
Defines syntax decisions and implementation plan across 7 issues:
- backtick command execution returning {code, stdout, stderr}
- ${expr} interpolation in backticks
- $SIGIL env var read/write
- argv parsing, piping, and redirection (future)
727 B
727 B
06 — Implement piping between commands
Status: open (post-core) Blocked by: #03, #04
Syntax
local result = `ls -l` | `grep ".lua"`
Implementation
- Connect stdout of one child to stdin of the next via
pipe()+dup2() - Build a pipeline of N processes, all forked and connected
- Only capture stdout/stderr of the final process
waitpid()all children, return exit code of last process
Challenge
Lua uses | for bitwise OR. The parser needs to disambiguate:
|between two command expressions → pipe|between numeric expressions → bitwise OR
This is resolvable because the parser knows the type of each subexpression — a backtick expression is always a command.