Mike, On Mon, Aug 3, 2015 at 12:34 PM, Mike Archbold <[email protected]> wrote:
> This is a great classic book on programming languages, the Programming > Language Landscape. > > > http://www.amazon.com/Programming-Language-Landscape-Semantics-Implementation/dp/0023758716/ref=sr_1_1?ie=UTF8&qid=1438630302&sr=8-1&keywords=programming+language+landscape > > My favorite chapter is "The Swamp of Complexity." In a nutshell -- > too many languages with too much crap in them! The author completely missed the REAL problem with language complexity - that when it becomes necessary to radically alter the execution, e.g. vectorize the program to run on a supercomputer, then the size of the compiler grows as the SQUARE of the size of the language (actually, n*(n-1)/2, the number of interactions of components). Where more than two elements must be considered together, there is often a cubic component that can swamp even the quadratic component. If you have twice the language complexity, it takes four (or eight) times as much compiler code to compile it to a radically different architecture than that of the language. THAT is why so many supercomputers start out with APL and FORTRAN compilers, and why C compilers only vectorize simple loops that utilize a small subset of the language. Of course, having lots of cute statements that all translate to arithmetic and IF statements don't affect the compiler complexity much at all. Unfortunately, this book never considered truly parallel implementations, where everything runs at once - but rather they considered "parallel" programming to be simple multi-threaded programing. Indeed, on page 6 they list "the" dozen classes of computer languages, none of which come close to what I am trying to create. Still - I got my dollar's worth. Thanks. Steve ================ > It looks like you can > get a copy for less than a buck.... > Mike A > > > On 8/3/15, Steve Richfield <[email protected]> wrote: > > Hi all, > > > > I am working on a high-level FPGA programming language, that should also > > serve better than existing languages as an AGI implementation language > and > > a robotics programming language. This is designed to be executed on FPGAs > > rather than CPUs, though a PC version is contemplated. > > > > Here are my early thoughts. All comments are welcome. > > > > Parallel Computing Language > > *Design Notes by Steve Richfield *as of Aug 2, 2015 > > > > The goal of PCL is to provide a language to express algorithms in > parallel > > form for easy compilation to either parallel or sequential platforms, > > rather than forcing programmers to express their algorithms in a probably > > inefficient sequential form, for a (nonexistent) compiler to translate > to a > > parallel form. > > > > > > The special need is to be able to translate to FPGA implementations, > which > > presently require efficient translation to be able to fit into existing > > hardware. > > > > > > *Existing Technology from which to Borrow* > > > > *APL structure:* In APL, everything is a matrix of varying > dimensionality, > > including zero dimensions (a simple variable). It includes numerous array > > operations as operators in the language. Unfortunately, its promoters > have > > adopted syntax reminiscent to Sanskrit, which is enough to chase away > > anyone not well versed in matrix inversions, etc. Some of the IBM-360 > > architecture was first worked out in APL. > > > > > > *Dartmouth BASIC MAT statements: *The original Dartmouth BASIC recognized > > MAT at the beginning of statements to indicate that the statements > > specified matrix operations, rather than operations on variables. Hence, > > *MAT > > C=A*B* multiplied matrix *A* by matrix *B*, and stored the result in > matrix > > *C*. APL-like procedure is MUCH less opaque in this syntax. > > > > > > *COBOL PICTURE clauses:* COBOL provided an easy (though now arcane) way > of > > easily describing variable structure, which could be easily extended to > > meet present needs. Specifying *PICTURE 9999*, which could be abbreviated > > *PIC > > 9(4)*, a programmer could easily state that a variable had to hold 4 > > decimal digit values. In our implementation, *PICTURE 111111111111* or > *PIC > > 1(12)* could specify a 12-bit field, as could *PICTURE 7777* or *PICTURE > > FFF*. COBOL also allowed for fixed-point notation, which is also > important > > in FPGA context, e.g. with *PICTURE 999V99* to represent 3 digits to the > > left and two digits to the right of the implied decimal point. Provision > > would have to also be made for logarithmic notation. Note that in > addition > > to precisely specifying “variables”, this also guides debuggers on how to > > display what they find. This approach would allow for specifying pipeline > > widths to be as narrow as possible for each operation. > > > > > > *FORTRAN Arithmetic Statement Functions:* FORTRAN provides a one-line way > > of specifying simple function subroutines, e.g. > > *RMS(A,B)=SQRT((A**2)+(B**2))* that are usually implemented by simple > > string substitution into their references, so they are executed as an > > in-line subroutine in C, but without the need to specify they are > in-line. > > Data chaining in complex operations would be easy to specify with such > > syntax. > > > > > > *Eliminating **GOTO** statements: *Parallel processing aside, there are > > plenty of good reasons to eliminate *GOTO* statements. In the process, we > > should probably eliminate everything else that specifies anything > > conditional beyond conditional storage of computed results. The presence > of > > a particular condition that necessitates particular processing should be > > handled as an event, though it would be possible to fake it by > translating > > conditional logic into an event handler. > > > > > > *All “procedure” will be event-driven:* Where sequence is needed, it will > > be triggered step-by-step, e.g. by *WHEN* statements. Where a long > sequence > > is needed, each step must be triggered by completing the previous step. > To > > avoid programming flags and *WHEN* clauses for each step, a *PROCEDURE* > > will be declared, that necessarily starts with a *WHEN* clause, after > which > > the compiler will assume that each step starts when the previous step has > > completed. There may be any number of procedures simultaneously active at > > any one time, but only one instance of any particular procedure, unless > it > > is declared as being *RECURSIVE* and/or *REENTRANT*. Where a procedure > > requires conditional operation within it, the conditional operation will > be > > triggered and entered via a *WHEN* statement. Note that complex *WHEN* > > statements, when implemented in hardware, only cost gates and NOT any > time. > > > > > > *Familiar Operations: *Familiar operations like SELECT ... CASE > statements > > will be provided, though they will “execute” in unfamiliar ways. For > > example, a SELECT statement will simultaneously “execute” all CASEs for > > which the stated conditions are satisfied. > > > > > > *Syntax:* Three different syntaxes will be supported, which can be > > intermixed on input. They are mathematical, familiar (similar to C), and > > verbose (similar to COBOL). For example, familiar *MAT C=A*B *in the > > example above would be simply *C=A*B* in mathematical form, and > *Multiply > > matrix A by matrix B giving matrix C* in verbose form. Error messages > from > > the compiler would show both the input and the equivalent verbose forms, > to > > show how the compiler interpreted the statements. > > > > > > *Early implementations:* Initially this PCL will be a publication > language > > to specify the construction of complex programmable logic. Then, a > > translator will be written in a portable language like C to translate > > programs from PCL to C so that programs can be tested on personal > > computers, etc. Then, translators will be written to translate to FPGAs > > programming languages *Verilog* and *VHDL*, and finally, FPGAs will be > > adapted to become better targets for code produced by this process, much > as > > IBM 360/370 mainframes were designed as prime targets for COBOL programs. > > > > > > *Other Applications:* This language comes VERY close to also meeting the > > needs for robotics applications, with many simultaneous tasks and close > > coupling to I/O, so it should be expanded to include anything that might > be > > missing to also serve robotics. > > > > > > *Comments:* PLEASE comment on this at any level, most especially what > > other languages might serve this need, what features of other languages > > should be incorporated, what it might be missing, what might be wrong, > etc. > > > > > > Steve > > > > > > > > ------------------------------------------- > > AGI > > Archives: https://www.listbox.com/member/archive/303/=now > > RSS Feed: > https://www.listbox.com/member/archive/rss/303/11943661-d9279dae > > Modify Your Subscription: > > https://www.listbox.com/member/?&; > > Powered by Listbox: http://www.listbox.com > > > > > ------------------------------------------- > AGI > Archives: https://www.listbox.com/member/archive/303/=now > RSS Feed: https://www.listbox.com/member/archive/rss/303/10443978-6f4c28ac > Modify Your Subscription: > https://www.listbox.com/member/?&; > Powered by Listbox: http://www.listbox.com > -- Full employment can be had with the stoke of a pen. Simply institute a six hour workday. That will easily create enough new jobs to bring back full employment. ------------------------------------------- AGI Archives: https://www.listbox.com/member/archive/303/=now RSS Feed: https://www.listbox.com/member/archive/rss/303/21088071-f452e424 Modify Your Subscription: https://www.listbox.com/member/?member_id=21088071&id_secret=21088071-58d57657 Powered by Listbox: http://www.listbox.com
