nik/lush

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Cormac Shannon db6f39a2a4 Add project issues for lush (Lua + shell) features

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)

2026-02-18 19:08:59 +00:00

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05 — Implement environment variable access (read/write)

Status: open Blocked by: #01

Add syntax for reading and writing environment variables directly from Lua.

Option 1 — `export` keyword

local var = "my data"
export var                    -- exports existing local to env
export other_var = "my data"  -- creates + exports

New reserved word export in lexer
export var looks up the local's value by name and calls setenv()
export x = val combines declaration with setenv()

Option 2 — `$` sigil

local dir = $PWD              -- getenv("PWD")
$PWD = "/"                    -- setenv("PWD", "/")
$MY_ENV_VAR = "data"          -- setenv("MY_ENV_VAR", "data")

$NAME as expression → getenv("NAME"), returns string or nil
$NAME = expr as statement → setenv("NAME", tostring(expr))
New token type in lexer for $ + identifier

Implementation touches

llex.c / llex.h — new token(s) or reserved word
lparser.c — new expression/statement rules
Runtime calls getenv() / setenv() — standard C, no shell needed
Non-existent env var → return nil