OlegKobchenko/Explicit Definitions

Contents

Common Uses
Uncommon Uses
1. Double Explicit
2. Simultaneous Assignment
See Also

Common Uses

Default x

One-liner

   v=: 4 : 'x+y'
   v
4 : 'x+y'
   (1&$:) : v
1&$: :v
   (1&$:) : v f.
1&$: :(4 : 'x+y')

Multi-liner

   w=: 4 : 0
  a=. y
  x+a
)

   (1&$:) : w f.
1&$: :(4 : 0)
  a=. y
  x+a
)

Attaching Rank

Separate and common monad/dyad ranks

   ((1&$:)"1) : (w"0) f.  NB. both ranks
1&$:"1 :(4 : 0"0)
  a=. y
  x+a
)

Common rank and separate rank

   w1=: (1&$:) : w"0 f.
   w1
1&$: :(4 : 0)"0
  a=. y
  x+a
)
   w2=: (1&$:) : (w"0) f.
   w2
1&$: :(4 : 0"0)
  a=. y
  x+a
)
   w1 b.0
0 0 0
   w2 b.0
_ 0 0

Attaching Other Conjunctions

Explicit conjunction provides just an ordinary J expression, which can be combined with other conjunctions and trains

Attaching each

   u=. 3 : 'y+1'&.>
   u i.3
+-+-+-+
|1|2|3|
+-+-+-+

Uncommon Uses

Double Explicit

   z2=: 3 : 0"0 : (4 : 0"0)
a=.y
x+y
)
a=.y
y+1
)
   z2
3 : 0"0 :(4 : 0"0)
a=.y
x+y
)
a=.y
y+1
)

$/!\$ Order of "declaration" should be monad : dyad, while the order of bodies is dyad ) monad ), because the declaration line is executed from right to left. Thanks to JuneKim for clarification.

Simultaneous Assignment

Compound declaration can be used in many cases, such as simultaneous assignment

   '`a b c'=: (4 :0)`(4 :0)`(4 :0)
x+y
)
x-y
)
x*y
)
   a
4 : 'x*y'
   b
4 : 'x-y'
   c
4 : 'x+y'