# macros — directory + tracing helpers
A handful of `#[macro_export]` macros auto-imported via `use
lighty_core::*;` or directly by name (`use lighty_core::mkdir;`).
## Directory helpers
All are async-aware: they use `tokio::fs::create_dir_all` under the
hood.
```rust
use lighty_core::{mkdir, try_mkdir, join_and_mkdir, join_and_mkdir_vec};
use std::path::Path;
#[tokio::main]
async fn main() -> std::io::Result<()> {
let base = Path::new("/tmp/launcher");
// Fire-and-forget — logs errors via trace_error!, swallows them
mkdir!(base);
// Propagates io::Error — use when failure should stop the pipeline
try_mkdir!(base)?;
// Join then mkdir, returns PathBuf
let mods = join_and_mkdir!(base, "instances/foo/mods");
// Sequence of joins, each level created
let world = join_and_mkdir_vec!(base, &["instances", "foo", "saves", "world1"]);
println!("{} / {}", mods.display(), world.display());
Ok(())
}
```
`mkdir_blocking!` exists for non-async contexts and runs the
`create_dir_all` inside `spawn_blocking`.
## Tracing macros
```rust
use lighty_core::{trace_debug, trace_info, trace_warn, trace_error};
fn process(path: &str) {
trace_info!("processing {}", path);
if path.is_empty() {
trace_warn!("empty path");
return;
}
trace_debug!("ok");
}
```
Structured fields work too (forwarded to `tracing::*!`):
```rust
use lighty_core::trace_info;
trace_info!(
version = "1.21.1",
loader = "fabric",
"launching instance"
);
```
Without the `tracing` Cargo feature, all four macros and `time_it!`
expand to no-ops — no runtime cost.
## `time_it!`
Logs the elapsed `Duration` of any expression at `DEBUG` level:
```rust
use lighty_core::time_it;
# fn expensive() -> i32 { 42 }
let result = time_it!("expensive op", expensive());
# let _ = result;
```
Output (with tracing on):
```
DEBUG label="expensive op" elapsed=12.3ms "Operation completed"
```
## Imports
The macros are exported at the crate root, so either of these works:
```rust
use lighty_core::{mkdir, trace_info};
// or
use lighty_core::*;
```
## See also
- [`how-to-use.md`](./how-to-use.md) — full walkthrough
- [`tracing` crate docs](https://docs.rs/tracing) — what the tracing
macros expand into when the feature is on