On Fri, Dec 11, 2015 at 7:55 AM, Brian Adkins <lojicdot...@gmail.com> wrote: > Excuse my ignorance of Racket internals & implementation, but I'm curious > about why the module system is implemented in C vs. Racket. Can someone who > is familiar with it provide some insight?
I'll do my best. A large number of features are implemented in C. Generally, you could divide those features in C into the categories "runtime", "virtual machine", and "compiler". (Don't read too much in to this division because the compiler is available at runtime and they are all primitive functions of the virtual machine.) By virtual machine, I mean the execution of byte-code forms, like making closures, doing garbage collection, making lists, and other data structures, connecting to C, etc. By runtime, I mean useful functions like filtering lists, converting numbers to do arithmetic, printing to ports, etc. By compiler, I mean expanding syntax then compiling it into byte-code. Historically, I'd say that these are all together in C because our macro system means the compiler has to run code inside of the virtual machine and have access to all those useful runtime functions. (Other things are in C because the FFI came "late" to Racket and we haven't gone back and implemented things like IO with the FFI, although Matthew did convert all of the GUI from C to Racket a few years ago.) Presently it would be pretty reasonable to convert C runtime code to Racket (to take a random example: a few years ago, `map` was moved[*] from C to Racket and performance improved due to the JIT. [* = it is actually still there but your Racket program's don't use it, just other internal C code calls that map.]. It's just unclear whether that's a good use of resources at this time. Matthew plans on porting the syntax expander part of the compiler into Racket and another graduate student is working on converting the compiler itself to Racket. It is pretty implausible at this point to convert the VM itself and get rid of everything in the runtime. You might imagine that we could make a compiler turn the bytecode directly into assembly, but we'd still need to have a runtime written in something to do stuff like GC. But few languages like Racket (i.e. that have a runtime) do anything like that. I hope this is helpful and I hope it is accurate, Jay -- Jay McCarthy Associate Professor PLT @ CS @ UMass Lowell http://jeapostrophe.github.io "Wherefore, be not weary in well-doing, for ye are laying the foundation of a great work. And out of small things proceedeth that which is great." - D&C 64:33 -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
