New basic logging module using kx.log as reference

[DI-Dexter]

Log

log.q is the default logging implementation for di.* modules. It writes formatted lines to stdout and satisfies the log dependency contract expected by modules such as di.email.

Usage

log:use`di.log
log.trace[`mymodule;"entering function"]
log.debug[`mymodule;"value is 42"]
log.info[`mymodule;"starting up"]
log.warn[`mymodule;"disk usage above 80%"]
log.error[`mymodule;"connection failed"]
log.fatal[`mymodule;"unrecoverable error, shutting down"]

Output format:

2026-04-09T12:00:00.000000000 [TRACE] [mymodule] entering function
2026-04-09T12:00:00.001000000 [DEBUG] [mymodule] value is 42
2026-04-09T12:00:00.002000000 [INFO] [mymodule] starting up
2026-04-09T12:00:00.003000000 [WARN] [mymodule] disk usage above 80%
2026-04-09T12:00:00.004000000 [ERROR] [mymodule] connection failed
2026-04-09T12:00:00.005000000 [FATAL] [mymodule] unrecoverable error, shutting down

Injecting into other modules

All di.* modules that accept a log dependency expect a dictionary with keys `info`warn`error, each a function with signature {[ctx;msg]}.

log:use`di.log
logdep:`info`warn`error!(log.info;log.warn;log.error)

email:use`di.email
email.init[emailconfig;`log`send!(logdep;::)]

You can extend the injected dictionary with trace, debug, and fatal for modules that support them:

logdep:`trace`debug`info`warn`error`fatal!(log.trace;log.debug;log.info;log.warn;log.error;log.fatal)

createLog

createLog is a factory that returns an independent logger instance with level filtering, multiple output sinks, and configurable format templates. Each call to createLog produces a separate instance with its own state.

log:use`di.log
mylog:log.createLog[]

mylog.setlvl `warn                        / suppress trace, debug, info
mylog.info "this is suppressed"           / returns () silently
mylog.warn "this appears"

mylog.setfmt `syslog                      / switch to syslog format
mylog.addfmt[`compact;"$l $m"]           / add a custom format
mylog.setfmt `compact

mylog.add[2i;`error`fatal]               / add stderr sink for error and fatal
mylog.remove[1i;`trace]                  / remove stdout from trace level

Sinks

A sink is a handle (integer file descriptor or function) passed to add. If a function is provided it is called with the formatted line string. Built-in handles follow standard q conventions: 1i is stdout, 2i is stderr.

buf:();
capture:{[msg] buf,:enlist msg};         / function sink - captures output
mylog.add[capture;`info`warn`error]
mylog.info "captured"
buf                                      / ("2026-...captured\n")
mylog.remove[capture;`info]

Format templates

Three built-in formats are available:

Name	Template	Example output
basic (default)	$p $l PID[$i] HOST[$h] $m	2026-04-09T12:00:00.000000000 INFO PID[1234] HOST[myhost] message
syslog	<$s> $m	<6> message
raw	$m	message

Template variables: $p timestamp, $l level, $i PID, $h hostname, $m message, $s syslog severity number.

API

trace

Parameters: [ctx; msg]

Write a trace-level message to stdout.

• ctx — symbol context tag (e.g. `mymodule)
• msg — string message

debug

Parameters: [ctx; msg]

Write a debug-level message to stdout.

info

Parameters: [ctx; msg]

Write an info-level message to stdout.

warn

Parameters: [ctx; msg]

Write a warning-level message to stdout.

error

Parameters: [ctx; msg]

Write an error-level message to stdout.

fatal

Parameters: [ctx; msg]

Write a fatal-level message to stdout.

createLog

Parameters: none

Returns an independent logger instance as a dictionary of functions. Each call returns a new instance with isolated state.

Returned keys: `trace`debug`info`warn`error`fatal`add`remove`setfmt`getfmt`addfmt`setlvl`getlvl

Function	Parameters	Description
trace..fatal	[msg]	Write a message at the given level (filtered by active level)
setlvl	[lvl]	Set minimum level; one of `trace`debug`info`warn`error`fatal
getlvl	[_]	Return current minimum level
setfmt	[name]	Switch to a named format template
getfmt	[_]	Return current format name
addfmt	[name;template]	Register a new named format template
add	[handle;lvls]	Add a sink for one or more levels; returns the handle
remove	[handle;lvl]	Remove a sink from a level

Log dependency contract

The log dependency contract used across di.* modules requires a dictionary:

`info`warn`error!({[ctx;msg] ...};{[ctx;msg] ...};{[ctx;msg] ...})

di.log satisfies this contract. You can also supply any custom implementation with the same signatures.

[DI-Software-Engineering]

DIReview Summary

1 critical | 4 warning(s) | 0 suggestion(s)

⚠️ Spec check skipped — tracker lookup failed (NO_REF_FOUND). Standards axis only.

[DI-Software-Engineering]

DIReview Summary

0 critical | 3 warning(s) | 0 suggestion(s)

⚠️ Spec check skipped — tracker lookup failed (NO_REF_FOUND). Standards axis only.

[JamesMassey97]

addressed automated comments and added commits.

The main change compared to the initial commit on this is the logdict so that is once the log module is imported. It will run the createlog function and give the user a default dict to use. There is also default logs outside of this to align with existing example in consitency.md but I am not sure if this is necessary.