Hi all !I think that as long as you don't use any mutable variables, what Henry want's to do might be very similar to what I'm asking for. It even has some functionality which is an improvement compared to tacit expressions and which still is within the bounds you try to stay within in modern functional programming. The problem is that people make mistakes and that's why you create languages which prevents them, or at least forces the programmer to explicitly state that he's doing questionable things, for example by forcing him to explicitly declare mutable variables.
(3 : '((3 : ''<:y++/\y-~-.y'')''\''=y){."0 y')'\\\//\\\//'
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With Henrys notation:
(. ((. <:y++/\y-~-.y).'\'=y){."0 y).'\\\//\\\//'Inline definitions of adverbs and conjunctions will be really cool, of course.
Ooops... 3 (4 : '[ y=. x + y') 5 8 Cheers, Erling On 2017-09-27 18:13, Marc Simpson wrote:
Great. Erling, how does your proposal differ from the above (glossing over specifics like using [, ] etc.)? On Wed, Sep 27, 2017 at 9:06 AM, Henry Rich <[email protected]> wrote:You have my proposal right. It is like d-fns. There is no new added functionality - in fact there can't be, because every (. ). function is converted to an explicit definition. The benefit is ease of creating explicit entities, even if they are anonymous, multiline, or nested within other entities. Henry Rich On 9/27/2017 11:31 AM, Marc Simpson wrote:Simple question (avoiding the tacit-v, tacit-t etc. terminology so that we're all on the same page): Are you essentially proposing something akin to Dyalog's d-fns? See, for example, https://www.dyalog.com/uploads/documents/Papers/dfns.pdf. (We don't have lexical scope in J, so the comparison isn't exact.) As far as I can tell, the proposal is to provide a syntax for more easily abstracting over explicit expressions without requiring transformations to tacit form. (In other words, an improved '4 :'.) If this is the case, would you mind expanding on how your proposal relates to existing explicit definitions? Are there significant functional differences, or is this mainly a syntactic proposal? One thing that springs to mind is that a d-fn style approach makes nesting explicit definitions far more readable and concise. /M On Wed, Sep 27, 2017 at 7:43 AM, Erling Hellenäs <[email protected]> wrote:It's hard to understand what could possibly remain to explain. Well, lets see if something more happens in the discussion. I'll give up on the second and third question. /Erling On 2017-09-27 16:23, Henry Rich wrote:I am sorry, but I have not been able to make sense of the last several messages. JWithATwist is outside my area of interest. If you can describe this idea fairly precisely, and explain why it should be implemented, I will try to understand it. To me, yes, what you can do with a language is the only thing that counts. Henry Rich On 9/27/2017 10:13 AM, Erling Hellenäs wrote:So it would be relevant to discuss this request in terms of programmer productivity? Any opinions? /Erling? On 2017-09-27 16:01, Don Guinn wrote:If you want the most powerful programming language it has to be assembly. It can do everything that every other programming language can do and so much more. But what is the purpose of languages like J and C++? They are to make people more productive, not computers. On Sep 27, 2017 7:34 AM, "Erling Hellenäs" <[email protected]> wrote: Hi all ! See comments below. There are still two unanswered questions. You are not required to answer them, of course. Cheers, Erling Hellenäs On 2017-09-27 13:36, Henry Rich wrote:The syntax is that of explicit J but missing some things, like control words and assignment, and perhaps the ability to write multiline expressions. If it produces tacit J, it's also not going to be able to define modifiers. I don't know what question this answers. JWithATwist handles modifiersduring interpretation, in the same way I think tacit J does. To set them at runtime you might have to use the same tricks as normal tacit J. Yes, I imagine the tacit-v expressions to have the same functionality as normal tacit J. No control words and no assignment. I just don't see that having a new way to write tacit verbs is a changeworth making, if it doesn't allow something that the old way didn't.And what you can do with a language is the only thing that counts? C++ is a million times better than J? To discuss other arguments for and against the different notations would be of no use?Henry Rich On 9/27/2017 6:25 AM, Erling Hellenäs wrote:Hi all ! See comments below. Henry, you answered one of three questions. Cheers, Erling On 2017-09-27 11:09, Henry Rich wrote:I have trouble contributing to this because I don't understand your proposal as written. One thing I don't understand is why you call your new verbs 'tacit'. It appeared to me that they used ] and [ as tokens indicating the input arguments. That would make them explicit, by the definition of that word.We can call them something different, I just choose tacit-v expressions for the purpose of my request. They are very similar to tacit expressions. They have exactly the same functionality, just different syntax, and that syntax is the syntax of explicit J.The tacit language shows up inside lines of code. When you write sortedbycol1 =: (/: 1&{"1) array there a little tacit code there. We wouldn't want to lose that. The tacit-v expression would besortedbycol1 =: (: ] /: 1 {"1 ] ): if we choose the (: ): brackets. The brackets are needed here as long as present tacit J is the default. The tacit-t version can be written like this. sortedbycol1 =: /: 1&{"1 Brackets are automatically added, creating the hook. If we directly compare the notation, ] /: 1 {"1 ] is equivalent to ( /: 1&{"1 )@] if we write code that can be moved between a monadic and dyadic context without rewrite. However, as I said, the easiest implementation probably is to continue allowing the present tacit expressions in tacit-v expressions. In the long run you would probably not want both ways to express exactly the same thing, you would want to let the new tacit-v expressions replace the present tacit expressions as I see it. There is a question about how it could be done. One way is to not allow them in tacit-v expressions from the beginning, as I propose, but there are other ways. To block them from the beginning would make the first implementation much harder. sortedbycol1 =: (/: 1&{"1) sortedbycol1 i. _3 4 0 1 2 3 4 5 6 7 8 9 10 11All the uninflected delimiters are taken, and {. }. and {: }: and <..and <: >:; but (. ). and (: ): are available. It seems out of the question to redefine any of { } [ ] as they are used in so much existing J code. Henry Rich On 9/27/2017 4:33 AM, Erling Hellenäs wrote:Hi all! It seems like fast function definitions is only for creating explicit J verbs, adverbs and conjunctions? This means it is only vaguely related to my proposal of tacit verbs with explicit J syntax? Maybe the fast function definition discussion should therefore have it's own thread? Let's say we wanted to implement tacit-v verbs. -Is there a construct like { ... } or (. ... ). that could possibly be used for a new kind of bracket notation? -Would x and y or [ and ] be suitable as symbols of the left and right arguments? If so, which of them ? If not, what would be a suitable representation of the left and right argument ? -Could the interpreter be easily modified to allow the explicit J syntax in this new bracket construct, or would it be difficult or impossible to achieve? In the JWithATwist interpreter the difference between how brackets with explicit J code are handled and how tacit-v brackets are handled is about four lines of code. It think this indicates that this might not be such a revolutionary change in terms of actual code changes. Cheers, Erling On 2017-09-26 22:34, Henry Rich wrote:Good point, colorization. I never thought about that. The big difference between Fast Functions and 3 : functions is that Fast Functions are recognized when a script is loaded, instead of when the 3 : is executed. It is the fact that 3 : is executed like any other conjunction that prevents nesting of multiline verbs: the nested verb can't be defined until it is executed, and by then its definition is long gone. The innermost (. ). is analyzed and replaced by (m : string). The process continues for all nesting levels. This completes the prepass. The generated verbs - (m : string) forms - are handled as they are now, when the : is executed. That means nested verbs are not processed until they are encountered during execution. Linear representation is used to make the (3 : string) form atomic. Yes, you would need to balance (. . Henry Rich On 9/26/2017 4:02 PM, Raul Miller wrote:Prepass means essentially that this happens after word formation but before parsing. That does eliminate some problems, but creates new ones. It also suggests that you would be supporting explicit control words. But it also means that you need to put a lot more thought into how these would be represented (and stored) - there's no inherent point to using linear representation to "unparse" here. (Do inner (. ). definitions get reparsed every time the outer expression gets evaluated? That might be the simplest approach, but does require significant changes in explicit handling.) Multiline means that you get into behavior somewhat like you get when m :0 appears on a line. But getting out of that might be more complicated than it is now (because you might not know if you need ). or a sequence of them or ) to end it - for example after pasting something big into your session). The complexities introduced by multi-line probably means that interactive environments would want to colorize (. ). definitions (especially incomplete definitions while being entered) based on the presence/absence of mnuvxy seen so far (probably not the current line though). 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