X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?p=forth.jl.git;a=blobdiff_plain;f=README.md;h=a6e0645b2a34c19dcd6b0b5fa86dc14107186679;hp=3d343057150d7f0619a335ff64cf104b1fced2bd;hb=43cd7e6d8968a85ee9250033080268caafef5a47;hpb=7f340ee5c011228a63002d92c1f64ce316f6d987 diff --git a/README.md b/README.md index 3d34305..a6e0645 100644 --- a/README.md +++ b/README.md @@ -1 +1,123 @@ -# FORTH +# forth.jl + +A hobby implementation of a forth system atop the Julia scientific computing +language. It will almost certainly never be useful for any purpose besides +that which it has already fulfilled: forcing me to think quite carefully about +how forth works. + +This package owes a massive debt to the existence of the literate programming +project [JonesForth](https://rwmj.wordpress.com/2010/08/07/jonesforth-git-repository/), +which was an amazing read. To a large degree my package is simply a port of +that project from x86 assembly + forth to julia + forth, although the mapping +is in a few places non-trivial due to the fact that julia is a high level +language. During the bootstrapping process, a huge proportion (say 80%) of the +library code in src/lib.4th was directly copied from JonesForth. (The fact +that it was possible to reuse this code was satisfying in its own right!) Since +that time I've added a significant number of core definitions and modified some +of the others with the eventual aim of F83 compliance (discussed below). + +There's quite a lot to say about the implementation, especially due to its +high-level grounding, but that will have to wait for another time. + +## Installation + +forth.jl is not (and probably will never be) a registered julia package. To +install it, you will therefore need to use the following command: + + julia> Pkg.clone("https://github.com/tgvaughan/forth.jl") + +Currently, forth.jl **requires** Julia 0.6. (Incompatabilities exist between +0.6 and previous versions of julia, particularly the handling of [world age](https://github.com/JuliaLang/julia/pull/17057).) + +## Usage + +To start the interpreter/compiler running, simply enter the following at +the julia prompt: + + julia> import forth + julia> forth.run() + +The first thing the interpreter will do is compile the core definitions in +the library file. Once this is complete you can start entering forth commands: + + : star 42 emit ; ok + star * ok + +There's an example Mandelbrot Set drawing program included in the examples +directory. To run it, use the `INCLUDE-LIB` word to open the file and compile its +definitions: + + include-lib ../examples/mandelbrot.4th + Enter 'mandel' to draw the Mandelbrot Set. ok + mandel + * + + ** + ******** + ********* + ***** + *** ******************** + ****************************** **** + ********************************** + *************************************** + ******************************************** + ** * ******************************************* + ************* ********************************************* + ****************** ******************************************** + ******************* ******************************************** + ** * * ******************************************************************* + ******************* ******************************************* + ***************** ******************************************** + ************* ******************************************** + ** * ******************************************** + ******************************************** + ************************************** + *********************************** + ****************************** **** + ** ******************** + ***** + ******* + ********* + ** + ok + +(`INCLUDE-LIB` is exactly like INCLUDE, but includes files relative to thte +platform-dependent forth.jl src/ directory.) To exit, enter ^D on a blank line +or use the `BYE` word. + +## FORTH-83 Compliance + +One of my goals has been to have forth.jl contain as much of the +[F83 required word set](http://forth.sourceforge.net/standard/fst83/fst83-12.htm) +as makes sense given the underlying VM. (Actually, my main goal goes a bit +beyond this: I want to forth.jl to be, with a couple of exceptions, compatible +with the description of forth contained in the second edition of Leo Brodie's +book "Starting Forth".) I'm fairly happy with my progress so far. Of the +131 required F83 words, only 20 remain unimplemented. These words fall into +two categories: those I may possibly implement at some point, and those that I +do not intend to ever implement for reasons of obsolescence or incompatibility +with the design of the VM. + +### F83 Words that may be implemented someday + + # #> #S -TRAILING <# + +These words all have to do with number to string conversion, something I've +not been interested in enough yet to get on top of. + +### F83 Words that won't be implemented + + D+ D< DNEGATE U< UM* UM/MOD BLOCK BUFFER FLUSH + SAVE-BUFFERS UPDATE BLK HOLD LOAD FORTH-83 + +These words don't make sense to implement. The double-length integer words are +useless because the smallest unit of memory in our VM is a full 64 bit +integer. For the same reason, there's no point in dealing with unsigned values +just to gain access to another bit. The block I/O words don't make sense because +we have access to a filesystem via the OS. + +## License + +This package is free software and is distributed under version 3.0 of the GNU +General Public License, which may be found in the file LICENSE in this +directory.