>From: Jose Mario Quintana <[EMAIL PROTECTED]>
> That is right! Instead of the current behavior, (using symbolic verbs to
> illustrate),
>
> (u v)Y
> (Y u (v Y))
> X(u v)Y
> (X u (v Y))
>
> (u v vv)Y
> ((u Y) v (vv Y))
> X(u v vv)Y
> ((X u Y) v (X vv Y))
>
> One could have had, , as you suggested,
>
> (u v)Y
> (u (v Y))
> X(u v)Y NB. No change
> (X u (v Y))
>
> and I would even consider,
>
> (u v vv)Y
> (u (v (vv Y)))
> X(u v vv)Y NB. (No structural change, but without any assumed
> order of execution regarding u vs. vv!)
> ((X u Y) v (X vv Y))
>
I built the verb AltParse and the adverb Code to have an inefficient but
functional playground for testing an alternative J by means of modifying the
parsing rules; a sample session follws.
NB. Symbolic verbs and nouns...
f=: ('('"_ , 'f '"_ , ] , ')'"_) :('('"_ , [ , ' f '"_ , ] , ')'"_)
g=: ('('"_ , 'g '"_ , ] , ')'"_) :('('"_ , [ , ' g '"_ , ] , ')'"_)
h=: ('('"_ , 'h '"_ , ] , ')'"_) :('('"_ , [ , ' h '"_ , ] , ')'"_)
X=. 'X' [ Y=. 'Y'
f X
(f X)
X g Y
(X g Y)
NB. Standard trains...
(f g) Y
(Y f (g Y))
X (f g) Y
(X f (g Y))
(f g h) Y
((f Y) g (h Y))
X (f g h) Y
((X f Y) g (X h Y))
AltParse Code
NB. Alternative trains...
(f g) Y
X (f g) Y
(f g h) Y
X (f g h) Y
NB. Sample coding...
(>: >: >: >:) 0
((>: >:) (>: >:)) 0
SumOfSquares=: +/ *:
SumOfSquares i. 4
NB. The standard train rules still apply for the internal behavior of f g h...
f Y
X f Y
NB. However, we could redefine them according to the alternative rules. For
example,
f
NB. can be redefined as,
f=: (('('"_ , 'f '"_ , ] , ')'"_)~ :('('"_ , [ , ' f '"_ , ] , ')'"_))
f X
X f Y
..
)
( f g ) Y
'(f (g Y))'
(f (g Y))
X ( f g ) Y
'(X f (g Y))'
(X f (g Y))
( f g h ) Y
'(f (g (h Y)))'
(f (g (h Y)))
X ( f g h ) Y
'((X f Y) g (X h Y))'
((X f Y) g (X h Y))
( >: >: >: >: ) 0
4
4
( ( >: >: ) ( >: >: ) ) 0
4
4
SumOfSquares =: + / *:
+/@:*: :(+/ *:)
+/@:*: :(+/ *:)
SumOfSquares i. 4
14
14
f Y
'(f Y)'
(f Y)
X f Y
'(X f Y)'
(X f Y)
f
f
('('"_ , 'f '"_ , ] , ')'"_) :('('"_ , [ , ' f '"_ , ] , ')'"_)
f =: ( ( '(' " _ , 'f ' " _ , ] , ')' " _ ) ~ : ( '(' " _ , [ , ' f ' " _ , ] ,
')' " _ ) )
'('"_@:,@:('f '"_@:,@:(]@:,@:(')'"_) :(] , ')'"_)) :('f '"_ , ]@:,@:(')'"_)
:(] , ')'"_))) :('('"_ , 'f '"_@:,@:(]@:,@:(')'"_) :(] , ')'"_)) :('f '"_ ,
]@:,@:(')'"_) :(] , ')'"_)))~ :('('"_ , [@:,@:(' f '"_@:,@:(]@:,@:(')'"_) :(] ,
')'"_)) :(' f '"_ , ]@:,@:(')'"_) :(] , ')'"_))) :([ , ' f
'"_@:,@:(]@:,@:(')'"_) :(] , ')'"_)) :(' f '"_ , ]@:,@:(')'"_) :(] , ')'"_))))
'('"_@:,@:('f '"_@:,@:(]@:,@:(')'"_) :(] , ')'"_)) :('f '"_ , ]@:,@:(')'"_) :(]
, ')'"_))) :('('"_ , 'f '"_@:,@:(]@:,@:(')'"_) :(] , ')'"_)) :('f '"_ ,
]@:,@:(')'"_) :(] , ')'"_)))~ :('('"_ , [@:,@:(' f '"_@:,@:(]@:,@:(')'"_) :(] ,
')'"_)) :(' f '"_ , ]@:,...
f X
'(f X)'
(f X)
X f Y
'(X f Y)'
(X f Y)
..
..
..
After playing around with this alter J, the suggestion for this alternative
monadic hook and fork does not seem to be a good idea anymore.
AltParse works by intercepting and modifying (when is necessary) J sentences as
they are being interpreted by Roger Stokes’ EVM parser cited in Learning J. In
the sample session (u v) is replaced by (u@:v) : (u v) and (u v w) by (u@:v@:w)
: (u v w). (It is a tedious process to set a modification up for an alter J
but I could provide directly the code if anyone is interested.)
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