ANN: goluago peek preview 2

[Mateusz Czaplinski <czapkofan@...>]

(posted to: lua-l@lists.lua.org, golang-nuts@googlegroups.com)

Library goluago aims to become a port of Lua 5.1 interpreter to Go
Language Toolchain
(first 8c/6c/5c, ultimately maybe pure Go).

The library is at early stage of development (not feature complete/not ready
for production use), but some important goals were already completed
successfully:

STATUS
------

### What works - new in preview 2:

  * [MILESTONE] parsing & compiling Lua scripts to bytecode (via
luaL_loadbuffer())
  * [Lua] standard libraries: basic library (print(), ipairs(),
assert(), loadstring(), etc.)
  * [Lua] passes parts of the Lua testsuite (tested on fragment of "calls.lua")
  * [API] basic strings API (lua_pushlstring(), lua_tolstring())
  * [API] exposing Go funcs into Lua (lua_pushgofunction(), lua_dump())
  * [tools] Lua script for embedding Lua testsuite parts in Go unit
tests (wrap-test.lua)
  * [API, Lua] string <-> number conversions

### What works since preview 1:

  * [API] creating/destroying new Lua state (luaL_newstate(), lua_close())
  * [API] basic integer operations on stack (lua_pushinteger(),
lua_gettop(), lua_equal())
  * [API] running simple precompiled Lua code chunk
(luaL_loadbuffer(), lua_call(),
    tested on precompiled chunk "return 2+3")
  * compiled and tested on: x86 (8c+8g), x64 (6c+6g), Windows/Linux
  * [tools] Lua script to simplify generation of Go+C wrappers for
    Lua API functions (internal/gen_wrappers.lua)



WANTED / PLANS
--------------

### Crucial:

  * to implement (leveraging Go fmt.Sprintf) a simplified C sprintf() function,
    in extent enough to cover the handful of use cases present in Lua sources
    (this shall enable more descriptive errors from Lua internals, and make it
    possible to dump the Lua stack to screen via lua_tostring() for
easier debugging);
  * to fix/implement all needed C standard library functions marked with FIXME
    (leveraging Go standard library where possible)
    -- the embedded nyi() call shall emit a runtime panic when a stub
function is
    called, making them easier to spot.
  * specifically, employ better algorithm for the strstr() function, which now
    uses naive O(n*k) approach
  * MILESTONE: enable rest of the Lua standard library
  * MILESTONE: get goluago to pass the Lua 5.1 testsuite (lua5.1-tests/*.lua)
  * MILESTONE: expose full Lua API in Go (except functions not
compatible with Go)

### Would be nice-ies:

  * write unit tests for C standard library functions implemented for Lua;
  * improve C standard library
    * maybe use some non-GPL Open Source code (FreeBSD? some stdlib
for embedded systems?);
  * extract C standard library to separate package;
  * later, "ANSI C to Go translator", in extent needed by the Lua sources?

**NOTE:** you're welcome to contribute anything if you fancy, and not
necessarily
from this list. The points above are mostly ideas as to what I believe would be
most useful at this moment.


BACKGROUND INFO
---------------

### Go Language?

http://golang.org

Farly new language developed at Google. Authors are however experienced in
building and experimenting with programming languages (specifically C,
Limbo), with
notable uses, including OS development (Unix, Plan9/Inferno). Highly portable
(x86/x64, ARM; Linux/*nix, Windows, Mac OS X, other ports in progress), written
(bootstrapped) in C. BSD-style licensed. Popularity hard to determine
given short
time on market, but has several nice and interesting features and properties
(and I like it too).


INSTALLATION
------------

You need the Go language toolkit version 1 (see: http://golang.org).
With the environment properly set up, type:

    go get github.com/akavel/goluago/internal
    go test github.com/akavel/goluago/internal

To retrieve and run a sample program:

    go get github.com/akavel/goluago/testlua
    cd $GOROOT   # or, see $GOPATH; on Windows %GOROOT%, %GOPATH%
    bin/testlua  # on Windows: bin\testlua.exe


/Mateusz Czapliński.