R has some really crazy metaprogramming facilities. This might sound strange coming from Python, which is already very dynamic - but R adds arbitrary infix operators, code-as-data, and environments (as in, collections of bindings, as used by variables and closures) as first class objects.
On top of that, in R, argument passing in function calls is call-by-name-and-lazy-value - meaning that for every argument, the function can either just treat it as a simple value (same semantics as normal pass-by-value, except evaluation is deferred until the first use), or it can obtain the entire expression used at the point of the call, and try to creatively interpret it.
This all makes it possible to do really impressive things with syntax that are implemented as pure libraries, with no changes to the main language.
It's true, the more I do in R, the more I wish that it had remained scheme compatible (originally, R was built on a scheme if I remember correctly).
My someday project is `#lang arcket` for Racket, which would allow people to use existing R code, and mix with Racket, with appropriate data.frame data structures and whatnot.
The problem will likely be similar to that with alternative Python implementations - because so many existing libraries in the ecosystem are written in C, an implementation that is not ABI-compatible with them is not attractive to most existing users.
No fundamental reason I know of that the C libraries for R could be used with Racket as well. After all, both R and Racket are able to do the FFI dance. Could the hypothetical R-in-Racket implementation sufficiently mimic the R FFI as to allow all R code to run without modification? Probably, maybe?
That's exactly the problem. R has a very specific API for its extensions - it's not just vanilla C, it's stuff like SEXP.
Although now that I think more about it, it's not quite as bad as Python, because the data structures are mostly opaque pointers (at least until someone uses USE_RINTERNALS - which people do sometimes, even though they're not supposed to), so all operations have to be done via functions, where you can map them accordingly.
You'd also need to emulate R's object litetime management scheme with Rf_protect etc; but that shouldn't be too difficult, either.
Oh, yeah, now that you mention it I have seen the SEXP and protect / unprotect stuff before. Maybe a hybrid approach of porting some of the core stuff / popular libraries to Racket's FFI would be more ideal if one were to do this for real.
Maybe aiming for "mostly compatible, with some porting work for a handful of the more popular non-R (C, Rcpp) packages would yield a better result in the end.
you should see Julia. There's a lot of syntactic sugar that borrows from the best of other languages, for example the pipe |> operator from elixir and do...end block syntax from ruby.
Full unicode is supported. Unicode pi is implemented to mean the pure mathematical entity, so at compile-time it is turned into an memory reference to the most possible exact value.
The metaprogramming in julia is so good I wrote a verilog DSL that transpiles specially written julia into compilable and verifiable verilog - in 3 days.
Yep, I'm aware of Julia. I hope it takes off - it certainly looks a lot better thought out than R, which is very idiosyncratic. So far, though, it's still a fledgling.
On top of that, in R, argument passing in function calls is call-by-name-and-lazy-value - meaning that for every argument, the function can either just treat it as a simple value (same semantics as normal pass-by-value, except evaluation is deferred until the first use), or it can obtain the entire expression used at the point of the call, and try to creatively interpret it.
This all makes it possible to do really impressive things with syntax that are implemented as pure libraries, with no changes to the main language.