use LUNA_LOG to set loglevel

docs/README.md

@@ -12,7 +12,7 @@ also works and returns the same table).
 | [`math`](math.md) | Additions to stock `math`: `round`, `clamp`, `isFinite`, `sign`, `scale`. |
 | [`table`](table.md) | Additions to stock `table`: map/filter/reduce, merge, deep-copy, aggregates, lookups, read-only proxy. |
 | [`os`](os.md) | Sandbox additions: `microtime` (sub-second clock) and async `sleep`. |
-| [`log`](log.md) | Level-tagged diagnostic logging (`trace`…`error`), gated by `RUST_LOG`. |
+| [`log`](log.md) | Level-tagged diagnostic logging (`trace`…`error`), gated by `LUNA_LOG`. |
 | [`sqlite`](sqlite.md) | Embedded SQLite: connect, query, parameters, transactions. |
 | [`http`](http.md) | HTTP/HTTPS client: requests, JSON, auth, cookie-jar sessions. |
 | [`fs`](fs.md) | Whole-file read/write and directory listing, behind a per-script folder permission system. |

docs/log.md

@@ -43,16 +43,16 @@ log.debug("request opts:", utils.dump(opts))
 ## Controlling what is shown
 
 Log output goes to **standard error**, and which levels are shown is set by the
-`RUST_LOG` environment variable. By default only `WARN` and `ERROR` appear:
+`LUNA_LOG` environment variable. By default only `WARN` and `ERROR` appear:
 
 ```sh
 luna script.lua                 # default: warnings and errors only
-RUST_LOG=info luna script.lua   # info and above
-RUST_LOG=debug luna script.lua  # debug and above
-RUST_LOG=trace luna script.lua  # everything
+LUNA_LOG=info luna script.lua   # info and above
+LUNA_LOG=debug luna script.lua  # debug and above
+LUNA_LOG=trace luna script.lua  # everything
 ```
 
-A level shows itself and everything more severe — `RUST_LOG=info` includes
+A level shows itself and everything more severe — `LUNA_LOG=info` includes
 `info`, `warn`, and `error` but not `debug` or `trace`. Messages below the active
 level are discarded cheaply, so leaving `log.debug` calls in place costs almost
 nothing when they are not enabled.
@@ -71,7 +71,7 @@ turn up or down without editing the script.
 
 ```lua
 local rows = con:query("SELECT * FROM users")
-log.info("fetched", #rows, "rows")    -- diagnostic; hidden unless RUST_LOG=info
+log.info("fetched", #rows, "rows")    -- diagnostic; hidden unless LUNA_LOG=info
 for _, r in ipairs(rows) do
     print(r.name)                      -- the actual result
 end
@@ -80,7 +80,7 @@ end
 ## Notes
 
 - **Always loaded.** No `require`; `log` is a global in every script.
-- **Quiet by default.** With no `RUST_LOG` set, only `warn`/`error` are emitted,
+- **Quiet by default.** With no `LUNA_LOG` set, only `warn`/`error` are emitted,
   so `info`/`debug`/`trace` are silent until you opt in.
 - **Arguments are stringified like `print`.** Multiple arguments are joined with
   tabs; tables print as their address, so use `utils.dump` for contents.

lua/demo/test.lua

@@ -54,7 +54,7 @@ local t2 = os.microtime()
 print("microtime ok:", t2 > t1)
 print("clock >= 0:", os.clock() >= 0)
 
-print("\n=== log (set RUST_LOG=info to see output on stderr) ===")
+print("\n=== log (set LUNA_LOG=info to see output on stderr) ===")
 log.info("hello from log.info")
 log.warn("hello from log.warn")
 

lua/demo/weather.lua

@@ -9,7 +9,7 @@
 --   table      map / ifilter / ifilterMap / min / max / mean / concat
 --   math       round / clamp / scale
 --   utils      try, dump
---   log        diagnostics on stderr (run with RUST_LOG=info to see them)
+--   log        diagnostics on stderr (run with LUNA_LOG=info to see them)
 --
 -- Data comes from https://wttr.in (no API key). The app prompts for a city,
 -- shows current conditions and a 3-day forecast, then lets you drill into a

lua/stubs/log.lua

@@ -1,20 +1,20 @@
 ---@meta
 -- Type stubs for the native `log` module: level-tagged diagnostics on stderr.
--- Visibility is controlled by RUST_LOG (default: warn and error only).
+-- Visibility is controlled by LUNA_LOG (default: warn and error only).
 -- Arguments are stringified like print and joined with tabs; use
 -- utils.dump(t) to log a table's contents. Reference: docs/log.md
 
 log = {}
 
----Very fine-grained, step-by-step detail. Shown with RUST_LOG=trace.
+---Very fine-grained, step-by-step detail. Shown with LUNA_LOG=trace.
 ---@param ... any
 function log.trace(...) end
 
----Developer diagnostics. Shown with RUST_LOG=debug.
+---Developer diagnostics. Shown with LUNA_LOG=debug.
 ---@param ... any
 function log.debug(...) end
 
----Normal high-level progress. Shown with RUST_LOG=info.
+---Normal high-level progress. Shown with LUNA_LOG=info.
 ---@param ... any
 function log.info(...) end
 

src/main.rs

@@ -59,7 +59,12 @@ impl Args {
 
 #[tokio::main]
 async fn main() {
-    env_logger::Builder::from_env(env_logger::Env::default().default_filter_or("warn")).init();
+    // `log` output is governed by $LUNA_LOG (and $LUNA_LOG_STYLE for color),
+    // not env_logger's default $RUST_LOG.
+    env_logger::Builder::from_env(
+        env_logger::Env::new().filter_or("LUNA_LOG", "warn").write_style("LUNA_LOG_STYLE"),
+    )
+    .init();
 
     // A panicking runtime must not strand the user on the alternate screen or
     // with a hidden cursor; restoring first also puts the panic message on