Writing J without @@: is like writing English without the letter 'e'. I
don't know what it shows, and it sounds funny, but look! I did it.
([: f g) <=> f@:g
([: f g)"({. g b. 0) <=> f@g
Henry Rich
On 12/21/2012 1:30 PM, Linda Alvord wrote:
So how can you write an equivalent explicit expression that will have the same
result of g without @ or @: ?
-----Original Message-----
From: programming-boun...@forums.jsoftware.com
[mailto:programming-boun...@forums.jsoftware.com] On Behalf Of bob therriault
Sent: Friday, December 21, 2012 1:02 PM
To: programm...@jsoftware.com
Subject: Re: [Jprogramming] A Tree Question
Hi LInda,
Since forks result in verbs of infinite rank (unless changed by the rank
conjunction), #@# is not actually equivalent to ([:##), although #@:# is. Watch
what happens when I swap @: for @
g=: 13 :'(=x) #@# y'
a=:0 0 1 0 1 5
b=:0 1 1 3 2 3
a g b
3 2 1
g1=:13 :'(=x) #@:# y'
a g1 b
3
Cheers, bob
On 2012-12-21, at 9:51 AM, Linda Alvord wrote:
Why do the trees of g and h appear to agree, but their results are
not the same?
]a=:?>:i.6
0 0 1 0 1 5
]b=:?>:i.6
0 1 1 3 2 3
f=: 13 :'x#/.y'
f
#/.
a f b
3 2 1
g=: 13 :'(=x) #@# y'
g
] #@#~ [: = [
a g b
3 2 1
NB. x u@v y ↔ u x v y
h=: 13 :'(=x) ([:##) y']
h
(] ([: # #)~ [: = [) ]
a h b
3
5!:4 <'g'
┌─ ]
│ ┌─ #
├─ ~ ─── @ ─┴─ #
──┤
│ ┌─ [:
└─────┼─ =
└─ [
5!:4 <'h'
┌─ ]
│ ┌─ [:
├─ ~ ──────┼─ #
┌───┤ └─ #
│ │ ┌─ [:
──┤ └─────┼─ =
│ └─ [
└─ ]
g
] #@#~ [: = [
h
(] ([: # #)~ [: = [) ]
Backtracking i and j are OK.
i=: 13 :'x #@# y'
i
#@#
a i b
7
j=: 13 :'#x#y'
j
[: # #
a j b
7
5!:4 <'i'
┌─ #
── @ ─┴─ #
5!:4 <'j'
┌─ [:
──┼─ #
└─ #
I have tried to include rank of the verbs but I haven’t found the
right combination if that is what is necessary.
Linda
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
