lily/logging

While the there is a logging package for Erlang, there isn’t one for JS, and since I’ve decided that the backend should also work on the JS target for some reason, this module is essentially a wrapper around the logging package for the Erlang target, alongside a JS version that aims to provide the exact same results.

See logging for more information, it’s the same hex package (the same logger used by mist and wisp) so log lines work cleanly with framework logs. On JavaScript, log lines are written to console.error / console.warn / console.info / console.debug by level, along with the colours used for the Erlang package. This works identically in browsers, Node, Bun, and Deno.

On Erlang, configure installs the logging package’s formatter and set_level sets the minimum level. On JavaScript, configure is a no-op and set_level maintains a programmatic level filter.

import lily/logging

pub fn main() {
  logging.configure()
  logging.set_level(logging.Info)
  logging.info("server ready")
  logging.auto_info(SomeMessage("hello"))  // logs "INFO SomeMessage(\"hello\")"
}

Types

Level

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Log severity. Matches the eight levels used by Erlang’s logger and the logging hex package.

pub type Level {
  Alert
  Critical
  Debug
  Emergency
  Error
  Info
  Notice
  Warning
}

Constructors

```
Alert
```
```
Critical
```
```
Debug
```
```
Emergency
```
```
Error
```
```
Info
```
```
Notice
```
```
Warning
```

Values

alert

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pub fn alert(message: String) -> Nil

Shortcut for log(Alert, message).

auto_alert

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pub fn auto_alert(value: a) -> Nil

Inspect value with string.inspect and log the result at Alert level.

auto_critical

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pub fn auto_critical(value: a) -> Nil

Inspect value with string.inspect and log the result at Critical level.

auto_debug

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pub fn auto_debug(value: a) -> Nil

Inspect value with string.inspect and log the result at Debug level.

auto_emergency

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pub fn auto_emergency(value: a) -> Nil

Inspect value with string.inspect and log the result at Emergency level.

auto_error

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pub fn auto_error(value: a) -> Nil

Inspect value with string.inspect and log the result at Error level.

auto_info

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pub fn auto_info(value: a) -> Nil

Inspect value with string.inspect and log the result at Info level. This is probably used the most.

server.on_message(srv, fn(msg, _model, _client_id) {
  logging.auto_info(msg)  // e.g. logs "INFO AddTodo(\"milk\")"
})

auto_log

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pub fn auto_log(level: Level, value: a) -> Nil

Inspect value with string.inspect and log the result at the given level.

auto_notice

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pub fn auto_notice(value: a) -> Nil

Inspect value with string.inspect and log the result at Notice level.

auto_warning

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pub fn auto_warning(value: a) -> Nil

Inspect value with string.inspect and log the result at Warning level.

configure

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pub fn configure() -> Nil

Configure the default logger. On Erlang, this installs the logging package’s pretty formatter and sets the level to Info. On JavaScript, this is a no-op — the console is always ready.

critical

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pub fn critical(message: String) -> Nil

Shortcut for log(Critical, message).

debug

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pub fn debug(message: String) -> Nil

Shortcut for log(Debug, message).

emergency

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pub fn emergency(message: String) -> Nil

Shortcut for log(Emergency, message).

error

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pub fn error(message: String) -> Nil

Shortcut for log(Error, message).

info

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pub fn info(message: String) -> Nil

Shortcut for log(Info, message).

log

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pub fn log(level: Level, message: String) -> Nil

Log a message at the given level.

notice

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pub fn notice(message: String) -> Nil

Shortcut for log(Notice, message).

set_level

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pub fn set_level(level: Level) -> Nil

Set the minimum level of log messages to emit. Messages below this level are suppressed.

On Erlang, delegates to logger:set_primary_config. On JavaScript, maintains a module-level threshold — useful on Node/Bun/Deno servers where DevTools is not available.

warning

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pub fn warning(message: String) -> Nil

Shortcut for log(Warning, message).