[ANN] Guile-SMC 0.6.2 released

[Artyom V. Poptsov]

Hello Guilers,

I'm pleased to announce Guile State Machine Compiler (Guile-SMC), version
0.6.2:
  https://github.com/artyom-poptsov/guile-smc/releases/tag/v0.6.2

This release fixes some new-found bugs, namely in the state-machine
profiler.  Also now it's possible to specify "pre-action" and
"post-action" procedures in PlantUML "legend" block.

Please see the list of notable changes below.

Guile-SMC 0.6.2 is backward-compatible with 0.6.0 and 0.6.1.


* What is Guile-SMC?

Guile-SMC is a state machine compiler that allows to describe finite
state machines (FSMs) in Scheme in terms of transition tables.  It is
capable to generate such transition tables from a PlantUML state
diagrams. [1]

Some of the key features:
- A transition table can be verified and checked for dead-ends and
  infinite loops.
- Guile-SMC FSMs gather statistics when they run (steps/transitions);
  the statistics can be used can be used to compare/analyze FSMs..
- There's an FSM profiler that runs on FSMs trace logs.  The profiler
  output shows how much time the FSM spends in each state.  This can be
  useful for optimization.
- The state machine compiler supports three "targets" for compilation: a
  regular "guile" target where the output FSM depends on Guile-SMC;
  "guile-standalone" target that produce an FSM that does not depend on
  Guile-SMC.
- Guile-SMC allows to run a FSM on-the-fly with a single "smc run"
  command -- see the docs and the examples for more information.
- Common context code for parsers that work with characters or bytes.
  This includes special data structures to provide memory for FSMs
  (although it is not required to use them; FSMs can use custom
  procedures and data structures.)

Guile-SMC comes with a Scheme program called 'smc' -- a state machine
compiler itself.  It produces a Scheme code for an FSM from the PlantUML
format.  This tool is meant to be called on a PlantUML file when a
program with a FSM is being built (for example, from a Makefile.)

I'm hoping that it will ease the burden of writing format parsers and
other useful GNU Guile libraries for the community.


* User-visible changes

--8<---------------cut here---------------start------------->8---
* Version 0.6.2 (2023-08-11)
** Bugfixes
*** =(smc context functional char)=: =pre-action= now always returns context
The procedure would return an undefined value when the input character is an
EOF object.  Now =pre-action= procedure always returns a context instance.

Also now the procedure handles cases when the input character is equal to
=#f=.
*** =(smc trace-context)=: Fix timestamp calculation
Procedures from the module now ensure that timestamps are always have positive
values.  When a negative value is detected then an error is issued.
*** =(smc cli command-profile)=: Fix time calculation
The profiler would fail to calculate correct time ranges.  Now the time is
calculated properly.
*** =(smc context oop generic)=: Add missing =(smc core log)= import
** Allow to set the FSM pre- and post-action in a PlantUML "legend" block
Guile-SMC now allows to set the pre/post actions for an FSM in the PlantUML 
"legend" block.
#+BEGIN_EXAMPLE plantuml
legend
pre-action:  custom-pre-action
post-action: custom-post-action
endlegend
#+END_EXAMPLE
** Add missing procedures for the =<fsm>= to get/set pre/post actions
Now the =(smc fsm)= module provides procedures to get and set pre- and 
post-actions.
** =(smc core log)= now registers the default logger
=(smc core log)= now registers the default logger under the name "guile-smc".
** =(smc core log)=: New procedure: =smc-log-default-logger=
This procedure allows to get the default logger instance.
** Update the documentation
--8<---------------cut here---------------end--------------->8---


* Usage examples

- Guile-INI -- INI[2] format parser:
  https://github.com/artyom-poptsov/guile-ics
- Guile-ICS -- iCalendar (RFC 5545) and vCard (RFC 6350) parser:
  https://github.com/artyom-poptsov/guile-ics
- Guile-PNG -- Pure Scheme Portable Network Graphics (PNG, RFC 2083)
  library:
  https://github.com/artyom-poptsov/guile-png

Happy hacking,

- Artyom

References:
1: https://plantuml.com/state-diagram
2: https://en.wikipedia.org/wiki/INI_file

-- 
Artyom "avp" Poptsov <poptsov.artyom@gmail.com>
Home page: https://memory-heap.org/~avp/
CADR Hackerspace co-founder: https://cadrspace.ru/
GPG: D0C2 EAC1 3310 822D 98DE  B57C E9C5 A2D9 0898 A02F

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