Re: [R] Formal definitions of R-language.
Murad Nayal [EMAIL PROTECTED] wrote: recursion, as far as I know, is inefficient in S/R. which tend to discourage purely functional programming. It's not so much that _recursion_ is slow, as that function calling is slow (whether recursive or not). A large part of the reason is that the S function calling convention was designed to favour human ease-of-use much more than ease of compilation. __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
Re: [R] Formal definitions of R-language.
On Mon, 21 Jul 2003, Richard A. O'Keefe wrote: Murad Nayal [EMAIL PROTECTED] wrote: recursion, as far as I know, is inefficient in S/R. which tend to discourage purely functional programming. It's not so much that _recursion_ is slow, as that function calling is slow (whether recursive or not). A large part of the reason is that the S function calling convention was designed to favour human ease-of-use much more than ease of compilation. The biggest problem with recursion in comparison to languages like Scheme and compiled LISPs may be that R can't eliminate any of the recursions. Even tail-recursion elimination (which is compulsory in Scheme) isn't possible without changing the semantics of the language, because functions like sys.frame() give access to all the frames that would be optimised out of existence. In my experience recursive functions run reasonably well in R until they hit the stack limit. -thomas __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
[R] Formal definitions of R-language.
Hello! Some CS-guys (the type who knows what Church formalism is) keep asking me questions about formal definitions of R-language that I can not answer (or even understand). Is there some freely available papers which I can throw at them where it would be explained is R functional/OOP/procedural language, does it use weak/strong, dynamic/static typization, does it use lazy or ...(do not know what) evaluation, what sort of garbage collector it uses? Thanks. __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
Re: [R] Formal definitions of R-language.
M.Kondrin wrote: Hello! Some CS-guys (the type who knows what Church formalism is) keep asking me questions about formal definitions of R-language that I can not answer (or even understand). Is there some freely available papers which I can throw at them where it would be explained is R functional/OOP/procedural language, does it use weak/strong, dynamic/static typization, does it use lazy or ...(do not know what) evaluation, what sort of garbage collector it uses? Thanks. R ships with a draft version of the manual R Language Definition. Another source is Venables Ripley (2000): S Programming, Springer. Uwe Ligges __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
Re: [R] Formal definitions of R-language.
Uwe Ligges wrote: M.Kondrin wrote: Hello! Some CS-guys (the type who knows what Church formalism is) keep asking me questions about formal definitions of R-language that I can not answer (or even understand). Is there some freely available papers which I can throw at them where it would be explained is R functional/OOP/procedural language, does it use weak/strong, dynamic/static typization, does it use lazy or ...(do not know what) evaluation, what sort of garbage collector it uses? Thanks. R ships with a draft version of the manual R Language Definition. Another source is Venables Ripley (2000): S Programming, Springer. Tell the CS-guys to grab the source code and chew on the LALR context-free grammar stuff in the file gram.y as in: R-1.7.1/src/main/gram.y R Language Definition lives at: http://cran.r-project.org/doc/manuals/R-lang.pdf __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
Re: [R] Formal definitions of R-language.
Douglas Trainor wrote: Uwe Ligges wrote: M.Kondrin wrote: Hello! Some CS-guys (the type who knows what Church formalism is) keep asking me questions about formal definitions of R-language that I can not answer (or even understand). Is there some freely available papers which I can throw at them where it would be explained is R functional/OOP/procedural language, does it use weak/strong, dynamic/static typization, does it use lazy or ...(do not know what) evaluation, what sort of garbage collector it uses? Thanks. R ships with a draft version of the manual R Language Definition. Another source is Venables Ripley (2000): S Programming, Springer. Tell the CS-guys to grab the source code and chew on the LALR context-free grammar stuff in the file gram.y as in: R-1.7.1/src/main/gram.y R Language Definition lives at: http://cran.r-project.org/doc/manuals/R-lang.pdf Thanks for your answers! I have already read R Language Definition but it is rather hmmm... evasive (?). For example: R belongs to a class of programming languages in which subroutines have the ability to modify or construct other subroutines and evaluate the result as an integral part of the language itself. This is similar to Lisp and Scheme and other languages of the functional programming variety, but in contrast to FORTRAN and the ALGOL family. Being similar to other functional programming language does not mean being the one itself, or does it? About typing it (not this passage I mean but RLD in a whole) said nothing. This thing about LALR is very good. I will try it on them. __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
Re: [R] Formal definitions of R-language.
some comments. I am still learning S/R so please let me know if I am missing something. M.Kondrin wrote: Hello! Some CS-guys (the type who knows what Church formalism is) keep asking me questions about formal definitions of R-language that I can not answer (or even understand). Is there some freely available papers which I can throw at them where it would be explained is R functional/OOP/procedural language, R is object oriented in the sense that the basic entities of the language (data elements, language elements etc.) are complex entities with type and defined behavior (objects). it has inheritance, polymorphism, operator overloading etc. you can define constructors for objects, but as far as I know no destructors (you can define clean up routines on libraries though). it has has elements of being a functional language like the fact that programs are composed of expressions that are turned into function objects that get evaluated. it also supports lambda expressions. it is not a pure functional language because functions can and do have side effects, it has persistent state and assignments, and it has flow of control statements. also, recursion, as far as I know, is inefficient in S/R. which tend to discourage purely functional programming. does it use weak/strong, weak typing. variables are not typed and keep type information once constructed. conversion between types is often automatic or can be programmed to be so, hence operations on disparate types can often be carried out. dynamic/static typization, it is dynamically typed. objects carry and supply type information at run time. types (as well as behavior) can (only) be defined at run time. the S-evaluator has to start first, it then constructs class and function definitions in the run-time environment. object type can be changed, modified and augmented at run time, at least with old style classes, (can you add or remove slots in the new style classes?). does it use lazy or ...(do not know what) evaluation, uses lazy evaluation of expressions. expressions are constructed by the S-evaluator, but not evaluated until needed. what sort of garbage collector it uses? No garbage collector. uses reference counting to discard objects that are no longer needed. Thanks. __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help -- Murad Nayal M.D. Ph.D. Department of Biochemistry and Molecular Biophysics College of Physicians and Surgeons of Columbia University 630 West 168th Street. New York, NY 10032 Tel: 212-305-6884 Fax: 212-305-6926 __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
Re: [R] Formal definitions of R-language.
On Thu, 17 Jul 2003, M.Kondrin wrote: Douglas Trainor wrote: Tell the CS-guys to grab the source code and chew on the LALR context-free grammar stuff in the file gram.y as in: R-1.7.1/src/main/gram.y R Language Definition lives at: http://cran.r-project.org/doc/manuals/R-lang.pdf Thanks for your answers! I don't think the grammar will actually answer their questions -- it doesn't specify a lot of the things you (they) are interested in. R doesn't really conform to purist classifications of languages (I tell C++ programmers that they would be happier if they think of the old method system as providing operator overloading rather objects). Luke Tierney would probably be the best person to reply but here's a stab at what they want: R has dynamic typing, and static lexical scoping. Functions are first-class objects but assignments to change variables are allowed and widely used. It has lazy evaluation of arguments. It has a non-copying garbage collector but does not have continuations or tail recursion optimisation. Operations that would naturally be written using dynamic scope or macros are faked by constructing expressions and evaluating them in other than the default environment. There are two object systems. Both provide polymorphism and (multiple) inheritance but do not restrict access to the internal structure of objects. Documentation for some things (methods, namespaces, the garbage collector) is at http://developer.r-project.org -thomas Thomas Lumley Assoc. Professor, Biostatistics [EMAIL PROTECTED] University of Washington, Seattle __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
Re: [R] Formal definitions of R-language.
[Oops. Accidentally sent only to D.Trainor first time around, even though it was intended mainly for M.Kondrin and the list] Douglas Trainor [EMAIL PROTECTED] writes: Uwe Ligges wrote: M.Kondrin wrote: Hello! Some CS-guys (the type who knows what Church formalism is) keep asking me questions about formal definitions of R-language that I can not answer (or even understand). Is there some freely available papers which I can throw at them where it would be explained is R functional/OOP/procedural language, does it use weak/strong, dynamic/static typization, does it use lazy or ...(do not know what) evaluation, what sort of garbage collector it uses? Thanks. R ships with a draft version of the manual R Language Definition. Another source is Venables Ripley (2000): S Programming, Springer. Tell the CS-guys to grab the source code and chew on the LALR context-free grammar stuff in the file gram.y as in: R-1.7.1/src/main/gram.y Don't. You'll get laughed out... The grammar of the language is essentially unrelated to the kind of categorizations CS people are looking for. Probably, Robert Gentleman or Luke Tierney are the guys best qualified to answer the question, but I can give a try: R is quite close to being Scheme plus syntactic sugar. Lexical scoping and function closures comes directly from Scheme and the internal structure of calls and functions (i.e. that they are equivalent to lists so that you can do things like e - quote(2+2) ; lapply(e,deparse) R is a functional language, with lazy evaluation and weak dynamic typing (a variable can change type at will: a - 1 ; a - a is allowed). Semantically, everything is copy-on-modify although some optimization tricks are used in the implementation to avoid the worst inefficiencies. Parameter passing is according to the pass-by-value illusion, i.e. what is really getting passed down to a function is a promise, which embodies the expression used in the call. This is at the core of the lazy evaluation mechanism: The result of the expression is not computed until needed. It also allows a function to get hold of the the expression itself: This is useful for labeling plots but it also allows some variants of pass-by-name-like semantics via evaluation in the environment of the caller. R is not object oriented in the same sense as Java or C++. We don't (generally) have methods that are semantically part of objects. However, we do have class-based function dispatch and generic functions, so that a function can do different things of different kind of objects, and - with the S4 class system - also for combinations of objects. Other distinctive features are that basic operations are vectorized, and that (somewhat perversly to LISP programmers) the traditional dotted-pair list lives quite deeply hidden from users, whereas the thing called list in R is really a generic vector where each element can be of different type. [This is not the only place where we have some rather unfortunate clashes in terminology between the S language (which is historically of APL descent) and the Scheme-like engine underneath.] Some implementation stuff is documented in sketches on developer.r-project.org (do read the opening paragraph!) and the intention is to have it documented in the R Language Definition, although that is still rather incomplete (and as Thomas Lumley once put it, it would be desirable if one could truthfully say that it is a work in progress). Also of course, there is the paper by Ross and Robert in JCGS. -- O__ Peter Dalgaard Blegdamsvej 3 c/ /'_ --- Dept. of Biostatistics 2200 Cph. N (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907 __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
Re: [R] Formal definitions of R-language.
Murad Nayal [EMAIL PROTECTED] writes: [Sensible stuff, except:] what sort of garbage collector it uses? No garbage collector. uses reference counting to discard objects that are no longer needed. No, R uses garbage collection with a generational scheme which looks more frequently at younger objects. The vector heap is handled with standard malloc-style memory allocation techniques (we once had code that would compact the heap during garbage collection, but it was found to be logically inconsistent: if you called a C routine and it called back into R and triggered a GC, it could happen that the C pointers were no longer pointing to the vectors they originally did). -- O__ Peter Dalgaard Blegdamsvej 3 c/ /'_ --- Dept. of Biostatistics 2200 Cph. N (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907 __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
