Let's break this down...
t=:".{{)n
3 1 4 1 2 1 1 8 8 3 6 7 3 3 4 3 6 4 2 1 8 2 7 7
_6 _8 _5 _8 _7 _8 _8 _1 _1 _6 _3 _2 _6 _6 _5 _6 _3 _5 _7 _8 _1 _7 _2 _2
0 0 0 0 0 0 0 1 1 0 1 1 0 0 0 0 1 0 0 0 1 0 1 1
}}-.LF
9!:3(1 6 5 4)
{:} }:
┌─────────────────┐
│┌─┬─────────────┐│
││2│┌────────┬──┐││
││ ││┌─┬────┐│}:│││
││ │││}│┌──┐││ │││
││ │││ ││{:│││ │││
││ │││ │└──┘││ │││
││ ││└─┴────┘│ │││
││ │└────────┴──┘││
│└─┴─────────────┘│
└─────────────────┘
({:} ) }:
{:} }:
┌─ } ─── {:
──┴─ }:
(Or, you could run dissect on your expression.)
Anyways, the point here is that ({:} }:) is a hook with two verbs. The
first verb is {:} and the second verb is }:
That means that an equivalent expression would be
t {:} t2=. }: t
This, in turn, means that this expression needs to find the result of
t {: t2 -- but that result does not exist, and the expression instead
gives you a domain error.
I hope this helps,
--
Raul
On Fri, Dec 10, 2021 at 10:24 AM R.E. Boss <[email protected]> wrote:
>
> I'm trying to solve the AdventOfCode puzzles, but at least half of my time I
> spend on troubles with J.
> Mostly I make mistakes, because the rules of J are less intuitive then I
> presumed, but there is also inexplicable behavior, so in the end, J remains a
> black box for me.
>
> t
> 3 1 4 1 2 1 1 8 8 3 6 7 3 3 4 3 6 4 2 1 8 2 7 7
> _6 _8 _5 _8 _7 _8 _8 _1 _1 _6 _3 _2 _6 _6 _5 _6 _3 _5 _7 _8 _1 _7 _2 _2
> 0 0 0 0 0 0 0 1 1 0 1 1 0 0 0 0 1 0 0 0 1 0 1 1
>
> ({:} }:)t
> |domain error
> | ({:}}:)t
>
> obviously }} is interpreted as part of a direct definition, red in JQT,
> despite my blank.
>
> (}:}~ {:) t
> |domain error
> | (}:}~{:)t
>
> black box in optima forma.
>
> Fortunately, as NUVOC mentions, } is a replacement of ( {"0 1&.|: ).
> But it cost me too much time, reason to timebox my efforts for AOC.
>
>
> R.E. Boss
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
