I am surprised to hear that the second solution produces a syntax error in
J604 even taking into account that J604 is quite old. I am pretty sure it
should work in J701 and definitely works in,
JVERSION
Engine: j805/j64/windows
Release: commercial/2016-12-11T08:02:16
Library: 8.05.10
Qt IDE: 1.5.3s/5.6.2
Platform: Win 64
Installer: J805 install
InstallPath: c:/program files/j 805
Contact: www.jsoftware.com
an=. <@:((,'0') (,&:<) ]) NB. Atomizing words (monadic verb)
train=. (<'`:')(0:`)(,^:)&6
f=. train@:([ , an@:]) f. NB. Non-compliant fixed tacit version
(*:`+:) f 4
64
It is a non-compliant solution because the verb train does not conform to
the rules of the Dictionary. In this instance, it seems to behave as any
other ordinary verb acting on a noun (which happens to be a gerund) and
producing a noun,
train (*:`+: , an 4)
64
However, this non-compliant verb is the counterpart of the adverb train
(`:6) and adverbs (and conjunctions) are capable to produce nouns, verbs
adverbs, and conjunctions. For example, (`:6) can produce a verb (a hook
in this illustration),
(*:`+:)(`:6)
*: +:
Consequently, the verb train can also do so even if it should not
(according to the Dictionary's rules),
train (*:`+:)
*: +:
This kind of verbs makes tacit writing in some instances easy as opposed to
very difficult (if they are forbidden). Most J programmers avoid them; I
embrace them because I like to write J only tacitly.
The third solution refers to a J fork (Jx) that, among other extensions,
provides additional primitives (and trains) which facilitate the use of
higher order functions directly; see my post [0].
I hope it helps.
[0] Jprogramming] Jx version 1.0 release
http://www.jsoftware.com/pipermail/programming/2017-August/048117.html
On Sun, Sep 24, 2017 at 2:35 PM, Rob Moore <robmoore...@gmail.com> wrote:
> Thanks for replying Raul, your solutions weren't what I was looking for,
> but I understand the confusion from my first explanation.
>
> Jose your first solution worked perfectly, thanks very much! The other two
> solutions you gave caused syntax errors for me, must be different versions,
> I'm on 604.
>
> What did you mean by compliant and non-compliant in your comments?
>
> Thanks,
>
> Rob
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