Although it is executed fro right to left,
it usually read and possibly written from
left to right. Speaking of a vector,
Length is "root" of the "sum" of "squares"
%: +/ *: 3 4
5
len=: %: @ +/ @: *:
len 3 4
5
or "sum" "under" "square"
+/ &.: *: 3 4
5
Moreover, this is the easiest and shortest way to say it.
--- Brian Schott <[EMAIL PROTECTED]> wrote:
> The example below shows how J code for one-liners
> can be entered on a keyboard more like it is developed -- at
> least by me. J parses from right to left and so I find that
> my code is written from right to left, but with the existing
> user interface the code must be entered left to right. While
> there is likely no way to completely alter this situation,
> the examples below may help a little.
>
> The example only works in the jconsole mode in
> unix/linux for now and I am not sure how to make it work in
> an ijx window -- maybe someone can help with that. I don't
> even know how to make it work in windows jconsole.
>
> The main idea is captured by the verb rc which
> parses tacit verbs pretty well. But one-liner explicit
> definitions are more complicated; the long bit of code which
> follows is a first crack at parsing one-line explicit verbs.
> See the full script far below, please.
>
> "."1;:^:_1"1(([: mt&,[:,&''''[:rc [: }:[: }.])^:(mt&-:@{.))each@:;:;._1 temp
>
> I welcome suggestions.
>
> (B=)
>
> Brian Schott
> Atlanta, GA, USA
> schott DOT bee are eye eh en AT gee em ae eye el DOT com
> http://schott.selfip.net/~brian/
>
> NB. jread.ijs
> NB. 2/18/5
> NB. 4/10/6 revised
>
> NB. routines to facilitate one-liner definition writing
> NB. from left to right ******
>
> rc =: |.&.;:
> keyboardIn =: [: 1!:1 3: NB. unix only
>
> NB. usage: rc '[EMAIL PROTECTED]'
>
> NB. usage: read'' (in unix only)
> NB. enter as many lines as desired
> NB. then type Ctrl-D to break
>
> NB. this system gets confused by parens
> NB. so they must be entered backwards (see example below)
>
> mt =: ''''
> read =: monad define
> temp =: rc keyboardIn y.
> "."1;:^:_1"1(([: mt&,[:,&''''[:rc [: }:[: }.])^:(mt&-:@{.))each@:;:;._1 temp
> )
>
> test =: noun define
> read'' NB. press Ctrl-d to end
> %@:/+=:mean
> 'y. {. 2 / + ~ - 10 * >:' : 13=:rind
> }.&2 ; {.&)1+2(=:sparer
>
> NB. press Ctrl-D after the sparer definition above
> NB. then you can view the saved definitions by type
> NB. the following names
> mean
> rind
> sparer
> )
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
>
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