mes/doc/announce/ANNOUNCE-0.4

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