[Jprogramming] Expositional tacit

['Jim Russell' via Programming]

Perfect!
"Junctions" they are. 
Thank you, Roger. 

> On Dec 9, 2019, at 1:41 AM, Roger Hui <rogerhui.canada at gmail.com> wrote:
> 
> "Tacit definition", "tacit programming", etc. originated with Ken Iverson,
> and first appeared in the 1991 paper *Tacit Definition*
> <http://www.jsoftware.com/papers/TacitDefn.htm>.  Before that, phrases
> like +/, +@*/ were called "operator expressions" and were commonly used at
> IPSA in the 1980s.  The final piece that made tacit definition work was
> forks.  This is described in more detail in the 1991 paper.
> 
> A particular form of forks is (f0 , f1 , ... , fn) or (f0 ; f1 ; ... ; fn),
> where the odd-positioned verbs is , or ; or ,. or ...  See *J Introduction
> and Dictionary*, Sample topic 15
> <http://www.jsoftware.com/help/dictionary/samp15.htm>.
> 
> 
> 
>> On Sun, Dec 8, 2019 at 8:24 AM 'Jim Russell' via Programming <
>> programming at jsoftware.com> wrote:
>> 
>> Never having seen a name for Ken and Roger's official dictionary's
>> expression format:
>> X (exp1;...;expn) y
>> I am going to use the subject phrase, at least until someone corrects me.
>> 
>> Thanks to Jimmy Gauvin (and Brian), I now understand that this cryptic
>> format used throughout the dictionary is a (series) of tridents with a
>> middle ";" verb; hence each verb fork seeing the x and y arguments as a
>> result of the "normal" (as yet to be fully understood by me) evaluation of
>> verb trains. (Close enough?)
>> 
>> This was a real epiphany to me. (Ok, I'm slow!)
>> Now I wonder which came first?
>> 
>> My first recall of 'tacit expressions' was while at STSC; it was mentioned
>> as something the folks at IPSharp were doing. (Don't know if it was
>> implemented or not in their commercial APL System.)
>> 
>> Haven't seen it addressed in any of Roger's excellent history of J
>> articles; is any one willing to describe, or do a (perhaps Reflexive-ish)
>> article re the history of "expositional tacit?
>> 
>> 
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