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On Sun, 2 Jan 2005 campbell@xxxxxxxxxxxxxxxxxxxxxxxxxxx wrote: >On Sun, 2 Jan 2005, bear wrote: > >> Arrays are damned useful, and being able to write them succintly >> is damned useful. It's true enough that scheme code is mostly lists, >> but that doesn't mean that a succinct syntax for arrays wouldn't be >> very useful, nor does it mean that SRFI-10 syntax is good enough for >> everything that isn't a list. > >This is a completely undefended assertion. You claim that arrays >should have a succinct syntax without stating why that is so, and you >again fall back to the nebulous aesthetics to claim that SRFI 10 'isn't >good enough' for arrays. And your claim that it is good enough is based on what? Look, I'm going to quit responding on this subpoint: there is no reason whatsoever *EXCEPT* aesthetics to pick any external syntax over any other. You lost (so badly that you are now forced to disparage as "nebulous" the only possible argument), so deal with it. >> Different coders, different code. When I'm storing aggregations of >> things, I usually use vectors for access speed rather than lists. >> Doing so is extremely awkward in Scheme. I only use lists in code >> where they're either "the right thing" for that particular application, >> or I'm being deliberately lazy and not optimizing. > >Sorry, I meant '...more frequently than arrays in Lisp's syntax.' (It >was originally part of the first point, but, when splitting it off into >a separate point, I forgot to include the 'in literal syntax' part.) My source code in some cases is almost five percent literal vectors. A recent example: ;; transformation matrix for a camera right turn of 0.1 radians. (define right-turn-1 #( #((cos 0.1) (sin 0.1) 1.0 1.0) #((sin 0.1) (cos 0.1) 1.0 1.0) #(1.0 1.0 1.0 1.0) #(1.0 1.0 1.0 1.0))) I don't want a front-loaded syntax because it will push the indentation level over further than is convenient to work with. >> I even go so far >> as to implement "closure" arrays for succinct reference and mutation >> instead of going through vector-ref and vector-set!. Not being able >> to write an external form for such gets in my way. > >Perhaps you could elaborate on this: I don't quite understand what you >mean here. I define mutable arrays using a constructor that returns a pair of procedures - one for reference and one for mutation. So I can do something like this: (let ((m (closure-array 4 4))) (define foo (car m)) (define foo! (cdr m))) instead of (define foo (vector (make-vector 4) (make-vector 4) (make-vector 4) (make-vector 4))) and thereafter: (foo 2 3) instead of (vector-ref (vector-ref foo 2) 3) and (foo! 2 3 #\a) instead of (let ((z (vector-ref foo 2))) (vector-set! z 3 #\a) (vector-set! foo 2 z)) But this trick, however useful, is limited because the arrays I can use with it are actually procedures, and procedures lack a reliable read-write syntax. This is just one example of the crap I go through to circumvent the clumsiness of arrays in scheme, and one example of why I wish they were as natural (and succinct) as lists. >> How >> > often do you find yourself wanting to write a literal array, except >> > as the first argument to SRFI 47's MAKE-ARRAY? >> >> Geez, let me count the ways. Data tables for character properties. >> color palettes. Graphic sprites. Coordinate transformation matrices. >> cellular automata substructures. Default Window coordinate lists. >> Map data. Integrated-circuit diagrams. Alias tables for character >> names. Parallel Records. Tuple aggregates. Multi-Character tokens >> for protocol drivers. Image data. Compiler transition tables. Tax >> rate tables. Icons. Lists of countries, states, counties, and >> municipalities. Bus routes. Airline schedules. Cellular coverage >> areas. And the list goes on... > >Great. So you've listed a lot of applications for arrays. Now answer >the question I asked: how often do you find yourself in Scheme code >wanting to write literal arrays by hand? Look again at the list. Those are precisely what you asked for: all are applications of STATIC arrays. These are places where I want immutable arrays during runtime, and the only way to get an immutable anything in scheme is to write it directly. At least up through debugging, I write these directly, making them immutable. Bear