118 lines
4.9 KiB
Org Mode
118 lines
4.9 KiB
Org Mode
-*-mode:org-*-
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* Fully source-based bootstrapping
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** R5RS-like scheme interpreter
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This first part is prototyped in C by the mes.c core and Scheme
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bootstrap code in module/. Of course, while mes.c is pretty small it
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cannot serve as a fully source-based solution.
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The initial idea was to have the minimal core support LISP-1.5 (or
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something very close to that as a tribute to John McCarthy) and extend
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eval/apply from LISP-1.5 source with define, define-macro etc. and
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metamorphose into R6RS. It seemed to work but performance of the
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LISP-intepreted RRS was so bad (~1000x slower than initial LISP-1.5)
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that this track was abandoned after the initial ANNOUNCE.
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The route changed trying strike a balance between core size and
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performance: still writing as much as possible in Scheme, but having a
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mescc compiler that takes not more than some seconds to run.
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Now that the important bits of R5RS are done and R6RS's syntax-case
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comes in scope, mes.c has grown into ~1500LOC, some effort must
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probably be directed into making that smaller.
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** Move mes.c into hex?
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One idea is to use OrianJ's amazing self-hosting [[https://github.com/oriansj/stage0][stage0]] hex assembler
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and minimal bootstrap binaries and rewrite the mes.c core to directly
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bootstrap into Scheme.
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** Rewrite mes.c and generate hex?
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Another idea (thanks Rutger!) is to rewrite the mes.c core in a
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C/Assembly variant and have mescc produce the simple, annotated
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bootstrap binary.
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** R6RS's syntax-case
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Having syntax-case should enable Mes to run [[https://savannah.gnu.org/projects/nyacc][nyacc]], which comes with a
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full C parser.
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*** Get Andre van Tonder's portable syntax-case up. + This would avoid the psyntax.ss -> psyntax.pp -> psyntax.ss
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bootstrap problem with an elegantly small implementation.
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- Does this support the idea of a minimal mes.c core, or is too
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much Scheme support required in the core?
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*** Get a version of portable psyntax.pp up.
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+ Fully standard complient R6RS macros.
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+ Minimal mes.c core required (not even quasiquote?).
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- Sloooowwwww with intepreter?
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* Bugs
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** Core is too fat
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mes.c is ~1500 lines (~10,000LOC Assembly) which seems much too big to
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start translating it to assembly/hex.
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** (mes-use-module ...) is a fake, see module/mes/base.mes.
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All top level scripts and test files (scripts/*.mes tests/*.test)
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now include appropriate (mes-use-module ...) stanzas.
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This hack allows for scripts/includes.mes to generate the list of
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files to be prepended. Previously, this information was put in
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GNUmakefile.
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** Garbage collection?
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Mes is using malloc without freeing anything, memory is patient these
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days :-)
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** find/fix hygiene problem: see module/mes/match.scm ;; X vs x
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**
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** Actually do something useful, build: [[https://en.wikipedia.org/wiki/Tiny_C_Compiler][Tiny C Compiler]]
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* OLD: Booting from LISP-1.5 into Mes
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Mes started out experimenting with booting from a hex-coded minimal
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LISP-1.5 (prototype in mes.c), into an almost-RRS Scheme.
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When EOF is read, the LISP-1.5 machine calls loop2 from loop2.mes,
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which reads the rest of stdin and takes over control. The functions
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readenv, eval and apply-env in mes.mes introduced define, define-macro
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quasiquote and macro expansion.
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While this works, it's amazingly slow. We implemented a full reader
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in mes.c, which makes running mes:apply-env mes:eval somewhat
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bearable, still over 1000x slower than running mes.c.
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Bootstrapping has been removed and mes.c implements enough of RRS to
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run a macro-based define-syntax and syntax-rules.
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loop.mes and mes.mes are unused and lagging behind. Probably it's not
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worth considering this route without a VM. GNU Epsilon is taking the
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more usual VM-route to provide multiple personas. While that sounds
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neat, Lisp/Scheme, bootstrapping and trusted binaries are probably not
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in scope as there is no mention of such things; only ML is mentioned
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while Guile is used for bootstrapping.
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* Assorted ideas and info
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** C parser/compiler
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*** [[https://savannah.gnu.org/projects/nyacc][nyacc]]
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*** PEG: [[http://piumarta.com/software/peg/][parse C using PEG]]
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*** [[https://en.wikipedia.org/wiki/Tiny_C_Compiler][Tiny C Compiler]]
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*** [[http://www.t3x.org/subc/index.html][Sub C]]
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*** [[https://groups.google.com/forum/#!topic/comp.lang.lisp/VPuX0VsjTTE][C intepreter in LISP/Scheme/Python]]
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** C assembler/linker
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*** [[http://www.tldp.org/HOWTO/Assembly-HOWTO/linux.html][Assembly HOWTO]]
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*** System call clue bat
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Basically, you issue an int 0x80, with the __NR_syscallname number
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(from asm/unistd.h) in eax, and parameters (up to six) in ebx, ecx,
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edx, esi, edi, ebp respectively.
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*** ELF
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7f 45 4c 46
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*** [[http://www.muppetlabs.com/~breadbox/software/tiny/][Small ELF programs]]
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*** [[http://www.cirosantilli.com/elf-hello-world/][Elf hello world]]
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** RNRS
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*** [[http://www.scheme-reports.org/][Scheme Reports]]
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*** [[ftp://publications.ai.mit.edu/ai-publications/pdf/AIM-349.pdf][Scheme - Report on Scheme]]
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*** [[ftp://publications.ai.mit.edu/ai-publications/pdf/AIM-452.pdf][RRS - Revised Report on Scheme]]
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