How about
u/!.f y
which would be like u/y except that it would apply yn v f as the first
application of u .
This would not require explicitly concatenating u and f .
Henry Rich
On 2/3/2015 3:06 PM, R.E. Boss wrote:
It was said long before
http://www.jsoftware.com/pipermail/general/2006-September/027793.html
" What has been will be again, what has been done will be done again; there
is nothing new under the sun", Ecclesiastes 1:9
R.E. Boss
-----Original Message-----
From: [email protected] [mailto:programming-
[email protected]] On Behalf Of Marshall Lochbaum
Sent: dinsdag 3 februari 2015 20:39
To: [email protected]
Subject: Re: [Jprogramming] Fold/reduce with initial value?
Since nobody's said it directly yet, I will: it is impossible to do this
efficiently in pure J and I consider it one of the language's biggest
omissions.
In an ideal J, dyadic u/ would perform this task (and its current use,
table, would have a different name). The lack of a built-in adverb of
any sort to perform the task can have substantial performance
implications.
Marshall
On Tue, Feb 03, 2015 at 06:15:37PM +0200, Moon S wrote:
I have a list (l), some object (o) and a verb (v) modifying the object:
l = l_0 l_1 ... l_n
o_new = o_old v l_i
The list items and the object have different types. I want to apply all
the
list items to the object:
o_new = (...((o_old v l_0) v l_1) ... v l_n) NB. the order of items
doesn't matter
Currently I do it like this:
o =: o_old
3 : 'o =: y v o' "0 l
I suspect, there must be some built-in feature for that, like / or ^:,
so
that I could write e.g.
o_new =: o_old v REDUCE l, but I couldn't find a suitable
verb/adverb/conjunction.
Any help?
Thank you.
Georgiy Pruss.
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