mes/doc/announce/ANNOUNCE-0.4

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Subject: Mes 0.4 released
I am pleased to announce the release of Mes 0.4, representing 115
commits over barely two weeks. It now runs Nyacc and PEG and has much
reduced core.
* About
Mes aims to create an entirely source-based bootstrapping path. The
target is to [have GuixSD] boostrap from a minimal, easily inspectable
binary --that should be readable as source-- into something close to
R6RS Scheme.
As bootstrapping is presumably easiest and probably most fun with
Scheme, the next step for Mes is mescc: a C compiler/linker to
boostrap into GNU Gcc and GNU Guile, possibly via Tiny-CC.
It currently has an interpreter written in C (mes) with Garbage
Collector (Jam Scraper), a library of loadable Scheme modules--
notably Dominique Boucher's LALR[1], Pre-R6RS portable
syntax-case[2] with R7RS ellipsis, Nyacc[3] and Guile's PEG[4]
--and test suite just barely enough to support a simple REPL
(repl.mes) and a proof-of-concept C-compiler (mescc.mes) that
produces an elf from the simplest of C files.
Mes is inspired by The Maxwell Equations of Software: LISP-1.5[5]
-- John McCarthy page 13
* Download
git clone https://gitlab.com/janneke/mes
wget https://gitlab.com/janneke/mes/repository/archive.tar.gz?ref=v0.4 -O mes-0.4.tar.gz
Mes runs from the source tree and can also be built, packaged and
installed in Guix[SD] by the usual
guix package -f guix.scm
* Changes in 0.4 since 0.3
** Core
*** Improved performance.
Macros are now memoized; after expansion and before eval'ing the
expanded form, their input s-expression is replaced by the expansion.
This yields a nice performance improvement which finally allowed
moving all non-essential bits from the C-core into Scheme...including
the reader. The Scheme reader is much, much slower than the previous
C version, making Mes--again-- feel slow. Think of that as a feature.
*** Bootstrap with minimal reader in C.
The C-reader needs only support reading of words and lists
(s-expressions), line-comments to read the initial Scheme reader which
then takes over and handles reading of quoting, characters, strings,
block-comments.
*** Reduced size.
Total C size: ~1500LOC. The main Mes evaluator is now ~1000LOC
including cell creation and garbage collector. This code is able to
execute a Scheme program that has been loaded into memory. Another
~500LOC is spent to load a minimal Scheme program and to dump it, to
provide a small posix interface, math functions and do some error
reporting.
*** Programs can be dumped and loaded using --dump and --load.
** Language
*** Minimal syntactic exception support for Nyacc.
*** Minimal syntactic fluids support for Nyacc.
*** Keywords are now supported.
*** Cond now supports =>.
*** Guile's optargs: lambda* and define* are now supported.
*** #;-comments are now supported.
*** Non-nested #| |#-comments are now supported.
*** Quasisyntax is now supported.
*** R7RS syntax-rules with custom ellipsis, with-ellipsis are now supported.
*** 9 new [partial] modules
(mes fluids), (mes nyacc), (mes optargs), (mes pmatch), (mes peg),
(srfi srfi-13), (srfi srfi-9-psyntax), (srfi srfi-26), (srfi srfi-43),
(rnrs arithmetic bitwise), (sxml xpath)
*** 36 new functions
1+, 1-, abs, and=>, append-reverse, ash, char<=?, char<?, char>=?,
char>?, even?, filter, delete, delq, vector-copy, fold, fold-right,
getenv, iota, keyword->symbol list-head, list-tail, negative?, odd?,
positive?, remove!, remove, string->number, string-copy,
string-prefix?, string=, string=?, symbol->keyword symbol-append,
symbol-prefix?, unless, write, zero?.
** Noteworthy bug fixes
*** Macros are now memoized.
*** An error is reported when using a wrong number of arguments with a call.
*** Cond now evaluates its test clauses only once.
*** Append can also handle one argument.
*** For-each now supports 2 list arguments.
*** Map now supports 3 list arguments.
*** Backslash in string is supported.
*** Closure is not a pair.
*** All standard characters are supported.
*** Mescc now also runs in Guile.
Greetings,
Jan
[1] https://github.com/schemeway/lalr-scm
[2] https://www.cs.indiana.edu/chezscheme/syntax-case/old-psyntax.html
[3] https://www.nongnu.org/nyacc/
[4] https://www.gnu.org/software/guile/docs/master/guile.html/PEG-Parsing.html
[5] http://www.softwarepreservation.org/projects/LISP/book/LISP%201.5%20Programmers%20Manual.pdf