Changing noun values could be another reason to use the ". bind 'name' pattern, but another approach is to use a script with the noun definition preceding the verb definition.
Sensitivity to timing is an unfortunate characteristic of many things with real world relevance. One approach, of course, is to retreat from relevance. Another is to address the sequencing issues. Thanks, -- Raul On Sun, Oct 1, 2017 at 10:12 AM, Don Guinn <[email protected]> wrote: > That's true. But sometimes one forgets to redefine the tacit definition > when the noun changes. > > On Oct 1, 2017 7:58 AM, "Raul Miller" <[email protected]> wrote: > >> Note that that first "gotcha" can be reversed in contexts where it's a >> problem and not a feature. This might also be desirable when dealing >> with large nouns. >> >> The pattern is: ". bind 'name' >> >> When you use (". bind 'name') you are using a verb whose result is >> always the value of that name. (The verb has infinite rank and always >> ignores any argument(s).) >> >> Thanks, >> >> -- >> Raul >> >> >> On Sun, Oct 1, 2017 at 9:43 AM, Don Guinn <[email protected]> wrote: >> > Tacit expressions are really quite simple. They are different from >> > non-tacit expressions only by three simple rules. The fork, hook and >> chain >> > rule. Tacit expressions are identified by the absence of arguments >> included >> > in the expression. They are explained thoroughly in help, so there is no >> > sense in revisiting that. But these rules only affect how multiple verbs >> > interact. The modifiers, i.e. adverbs and conjunctions work identically >> in >> > tacit and non-tacit expressions. It is the modifiers that give much of >> the >> > power to J. >> > >> > People writing tacit tend to use modifiers a lot. They provide tremendous >> > flexibility in writing concise, compact code. Many find it unreadable. >> > Modifiers are used less in non-tacit expressions. Why I don't know. But >> > they could be used a lot more than they are in non-tacit expressions. >> > Perhaps as people learn the power of modifiers they tend to write more >> > tacit expressions. >> > >> > Some think that nouns cannot appear in tacit expressions. That is untrue. >> > They can be attached to verbs in tacit expressions, only not as arguments >> > to the entire expression. >> > >> > Notice that I refer to tacit and non-tacit expressions. That is because >> > they can be mixed in definitions. Explicit definitions can contain a >> > mixture of tacit and non-tacit expressions, even on a line of code. Tacit >> > definitions can contain explicit definitions as well. >> > >> > There are some gotchas in tacit. >> > >> > Tacit definitions use the values of nouns and user definitions at the >> time >> > of definition. Not the time of use. Say you use a noun named "abc" in a >> > tacit definition. Then later change the value of "abc" and use the tacit >> > definition. Oops! The definition still has the old value of "abc". >> > >> > Modifiers do not change how they work between tacit and non-tacit, but >> when >> > combined with verbs they define new verbs. Those new verbs now follow the >> > three rules of tacit. It looks like the modifiers are working >> differently, >> > but it is the new verb that is actually working differently. >> > >> > Tacit expressions can contain tacit expressions. When this happens it can >> > be a bit confusing figuring out what the arguments to the contained >> > expression are. >> > >> > Using very large nouns in a tacit definition can result in very large >> > definitions causing memory problems as the noun is copied into the >> > definition. This can cause problems, but it has interesting possibilities >> > for performance. Consider using (i.) inside a (for.) loop in an explicit >> > definition. Make a local tacit definition before the loop attaching the >> > huge noun to (i.) like this: (search=.hugenoun&i.). Then use (search) in >> > the loop. The overhead of preparing the search, including possibly >> building >> > a hash table is outside the loop. And the huge definition goes away when >> > the explicit definition completes. >> > >> > There are interesting possibilities when one considers using explicit >> verb >> > definitions in a tacit expression. Now you have a chance to do all those >> > naughty tricks like saving intermediate results to global names. >> > >> > To me it's not tacit that causes so many problems, it is the tremendous >> > flexibility provided by modifiers that provide a richness, complexity and >> > power to J. >> > ---------------------------------------------------------------------- >> > For information about J forums see http://www.jsoftware.com/forums.htm >> ---------------------------------------------------------------------- >> For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
