Re: Reference Manual
Hi Jonathan, > (if 'any1 any2 . prg) -> any > ... > I also don't get the "." between "any2" and "prg" - does that mean > something? Yes. As you probably know, the dot is used in "dotted pairs" in Lisp, as a result of a "cons" operation. In general, a list can be written recursively as (any . lst) e.g. : (1 . (2 3 4)) -> (1 2 3 4) A 'prg' is a list of 'exe's (executable expressions). So a call like (if (someCondition) (doThat) (doElse1) (doElse2) ) can be dissected into any1 (someCondition) any2 (doThat) prg ((doElse1) (doElse2)) : '(if (someCondition) (doThat) . ((doElse1) (doElse2))) -> (if (someCondition) (doThat) (doElse1) (doElse2)) > Is there any significance in the difference of "any2" and "prg". I would > have thought they were both "any" type parameters. In some sense, yes. 'any' is the most general type, it can be anything, i.e. a number, a symbol or a list. 'prg', however, is typically a list, so it better describes what 'if' expects. ♪♫ Alex -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe
Re: Reference Manual
Hi Jonathan, (and thanks Erik!) > in the docs I have with my source which is 3.1.11 I have the definition of > "if" as > > (if 'any1 'any2 . prg) -> any > > but on the web reference link (http://software-lab.de/doc/refI.html#if) it's > > (if 'any1 any2 . prg) -> any Very well observed! In fact, this was changed just recently. Quoting 'any2' was (arguably) wrong. This came up in a discussion in IRC. 'any1' is evaluated the normal, expected way, i.e. just upon function entry. So this must be "quoted" in the referece. 'any2', however, may be evaluated or not, depending on the outcome of 'any1' (as is also the case for the elements of 'prg'). So I would say 'any2' should not be quoted. (Note still another convention I'm using here in this mail: Writing 'any' in a *pair* of quotes does not refer to the *single* quote used for evaluated arguments in the reference, but indicates a markup) ♪♫ Alex -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe
RE: Reference Manual
Oh, I have more questions, but first I should clarify something I just noticed. in the docs I have with my source which is 3.1.11 I have the definition of "if" as (if 'any1 'any2 . prg) -> any but on the web reference link (http://software-lab.de/doc/refI.html#if) it's (if 'any1 any2 . prg) -> any note the difference in quoting for any2. Which is correct? Jonathan. -Original Message- From: picolisp@software-lab.de [mailto:picolisp@software-lab.de] On Behalf Of Erik Gustafson Sent: Tuesday, 13 October 2015 11:45 AM To: picolisp@software-lab.de Subject: Re: Reference Manual Hey Jonathan, Great questions! What is the significance of "any1" being quoted and "any2" not being quoted? > Quoted arguments, in the context of the Function Reference, mean that the argument is evaluated by the function. So (if) evaluates its first argument, any1, whereas the second argument, any2, is passed in unevaluated=
Re: Reference Manual
Hey Jonathan, Great questions! What is the significance of "any1" being quoted and "any2" not being quoted? > Quoted arguments, in the context of the Function Reference, mean that the argument is evaluated by the function. So (if) evaluates its first argument, any1, whereas the second argument, any2, is passed in unevaluated
Reference Manual
Hi, Newbie here. I'm a little puzzled by some features of the Reference manual. Eg for "if" (if 'any1 any2 . prg) -> any What is the significance of "any1" being quoted and "any2" not being quoted? I also don't get the "." between "any2" and "prg" - does that mean something? Is there any significance in the difference of "any2" and "prg". I would have thought they were both "any" type parameters. Thanks Jonathan.
Re: Reference Manual diagram conventions
Alexander Burger writes: In all these documentations, cells are always displayed in the form +-+-+ | CAR | CDR | +-+-+ The left half of the cell is the CAR, and the right half the CDR. Just as the cell resides in memory. The CAR is at the lower address, and the CAR at the higher. The important point is that the pointer *TO* a PicoLisp item may point to different parts of the cell: Ah, okay, now i understand. Confusing? No, i found your explanation succinct and clear - thank you! Alexis. -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe
Re: Reference Manual diagram conventions
Hi Rick, > I think (I’m speculating, that is) that the confusion was due to the > unusual (but not incorrect) choice of having key/val pairs stored in symbol > property lists as > > +-+-+ > | VAL | KEY | > +-+-+ > > where VAL is the the CAR position and KEY in the CDR position. There is not > right or wrong about this, that’s just how it works. I find this point very > interesting. I believe it has something to do with streamlining the > picolisp (C or asm) code regarding properties, but I don’t know for sure. > Alex? No, this is in fact a fundamentak design decision. It allows the 'var' concept to be extended to properties, using the 'prop' and '::' functions. If the value VAL of a property cell is in the CAR, all functions which accept a location (noted as 'var' argument in the reference) can directly operate on it. The KEY is relatively unimportant, it is only used internally to locate the cell in the property list. For example, give the symbol 'A' a property with KEY = 'cnt' and VAL zero: : (put 'A 'cnt 0) -> 0 If you get the property cell (the pair VAL / KEY above): : (prop 'A 'cnt) -> (0 . cnt) you see that the value is in the CAR and the KEY in the CDR. Now you can increment this: : (inc (prop 'A 'cnt)) -> 1 Check: : (get 'A 'cnt) -> 1 : (prop 'A 'cnt) -> (1 . cnt) Another examples with 'push': : (push (prop 'A 'lst) 1) -> 1 : (push (prop 'A 'lst) 2) -> 2 : (push (prop 'A 'lst) 3) -> 3 : (get 'A 'lst) -> (3 2 1) : (prop 'A 'lst) -> ((3 2 1) . lst) : (with 'A (println (pop (:: lst)) (pop (:: lst))) (push (:: lst) 7) (: lst) ) 3 2 -> (7 1) ♪♫ Alex -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe
Re: Reference Manual diagram conventions
AFAIK advantage is: varPtr = Val; as seen in @src/sym.c doSet: val(data(c1)) = data(c2);
Re: Reference Manual diagram conventions
I think (I’m speculating, that is) that the confusion was due to the unusual (but not incorrect) choice of having key/val pairs stored in symbol property lists as +-+-+ | VAL | KEY | +-+-+ where VAL is the the CAR position and KEY in the CDR position. There is not right or wrong about this, that’s just how it works. I find this point very interesting. I believe it has something to do with streamlining the picolisp (C or asm) code regarding properties, but I don’t know for sure. Alex?
Re: Reference Manual diagram conventions
Hi Alexis, > The "Symbols" section of the PicoLisp Reference Manual: > http://software-lab.de/doc/ref.html#symbol > seems to have the convention: > >+-+-+ | cdr | car | +-+-+ > > whereas the "Numbers" and "Lists" sections has the convention: > >+-+-+ | car | cdr | +-+-+ > > which, in an English-language left-to-right document, is what i > would expect. No, this is not the case. In all these documentations, cells are always displayed in the form +-+-+ | CAR | CDR | +-+-+ The left half of the cell is the CAR, and the right half the CDR. Just as the cell resides in memory. The CAR is at the lower address, and the CAR at the higher. The important point is that the pointer *TO* a PicoLisp item may point to different parts of the cell: 1. In case of a pair (list cell) it points to the address of the CAR Pair | V +-+-+ | CAR | CDR | +-+-+ 2. In case of a symbol, it points to address of the CDR part of the cell, which holds the value of the symbol: Symbol | V +-+-+ | | | VAL | +--+--+-+ Note that still the CAR part of that cell is on the left side. It holds a pointer to the symbol's tail. The CDR part of the cell holds VAL, the symbol's value. 3. Finally, a bignum cell is pointed to its "middle" Bignum | V +-+-+ | DIG | | | +-+--+--+ That is, it points to an address *inside* the cell, not to its starting address. Confusing? ♪♫ Alex -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe
Reference Manual diagram conventions
Hi all, The "Symbols" section of the PicoLisp Reference Manual: http://software-lab.de/doc/ref.html#symbol seems to have the convention: +-+-+ | cdr | car | +-+-+ whereas the "Numbers" and "Lists" sections has the convention: +-+-+ | car | cdr | +-+-+ which, in an English-language left-to-right document, is what i would expect. Is there a particular reason for the former? Alexis. -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe
