Like others, I'm learning to use j effectively on tiny smart phone
display. I had considered preprocessing source with m4 to produce long
j sentences. Considering m4 helped me finally understand eval. Eval
directly converts literals into j code. Now I have another option to
compose j.
Thank you all.
Eval =: 1 : 'a: 1 : m'
increase =: '([: $: >:)'
result =: '(])'
choose =: '(3 < |)'
(increase,'`',result,'@.',choose)Eval
([: $: >:)`]@.(3 < |)
(increase,'`',result,'@.',choose)Eval 1
4
NB. I have not found m4 for android.
Date: Tue, 29 Jul 2014 22:43:21 -0700
From: "'Pascal Jasmin' via Programming"<programm...@jsoftware.com>
To:"programm...@jsoftware.com" <programm...@jsoftware.com>
Subject: Re: [Jprogramming] recursive agenda with named components
Message-ID:
<1406699001.37116.yahoomail...@web122605.mail.ne1.yahoo.com>
Content-Type: text/plain; charset=iso-8859-1
? ?eval =:?1 : ' a: 1 : m'?
? ?A =: 1 : (,'u')
? ?eval2ger =:?3 : 'a=. A for_i. y do. a=. (>i) eval a ` end. '''' a'
a partial way of doing it,
? (eval2ger@:((<' f.') ,~ each ]) 'increment';'result')@.choose f.
([: $: >:)`]@.(3 < |)
eval2ger takes a boxed list of string expressions, and turns them into a gerund
expression. ?The other part "automates" adding f. inside the expression.
________________________________
From: David Lambert<b49p23t...@stny.rr.com>
To: programming<programm...@jsoftware.com>
Sent: Tuesday, July 29, 2014 10:05:54 PM
Subject: [Jprogramming] recursive agenda with named components
Suppose I have a recursive verb
? ? ([: $: >:)`]@.(3 < |)
And I want to name the components
? ? increment =: [: $: >:
? ? result =: ]
? ? choose =: 3 < |
? ? increment`result@.choose f.
3 : '[: $: >: y' :(4 : 'x [: $: >: y')`]@.(3 < |)
J carefully isolated recursion to the named verb
Thus I really want to, in symbolic language, Map f.
? ? (increment f.)`(result f.)@.(choose f.)
([: $: >:)`]@.(3 < |)
Or in this case, simply
? ? (increment f.)`result@.choose f.
([: $: >:)`]@.(3 < |)
Is there a way to map f. ?? I tried literals with Define (5!:0) but of
course I'd need to construct a complicated boxed structure.
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