[Jprogramming] Function creation, without creating subfunctions

[Raul Miller]

Actually, thinking about this further, the parenthesis around f are
not actually needed. But that is because f is a fork, and the default
behavior will be to construct a fork before incorporating the
definition of g. (If f was a hook, you would still need those parens.
The interpreter does not eliminate quite all unnecessary parenthesis
when representing verbs as their linear definitions - a few extra may
be included for cases where it seems likely that that will enhance
readability.)

Thanks,

-- 
Raul


On Sat, May 27, 2017 at 10:35 PM, Raul Miller <rauldmiller at gmail.com> wrote:
> Basically, you put the definition of f in parenthesis (though it
> already is, so no actual change needed there), and the definition of g
> in parenthesis.
>
> You can even get the interpreter to do this for you:
>
>    9!:3]5
>
>    make_move
> g f
>    make_move f.
> ((+. *. -.@:*.) +./) (1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 |.!.0~ 3 1 $ -)
>
> Though, I would be tempted to replace 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0
> with (15{.1) in a definition.
>
> I hope this helps,
>
> --
> Raul
>
>
> On Sat, May 27, 2017 at 10:28 PM, Michael Rice <limitcase at gmail.com> wrote:
>> NB. 15 position peg solitaire
>> NB. The board (position 5 initially vacant)
>>
>> NB.         0
>> NB.       1   2
>> NB.      3  4   5
>> NB.    6  7   8   9
>> NB.  10 11 12  13 14
>>
>>    xor =: ((+.)*.(-.@:*.))
>>    board =: 1 1 1 1 1 0 1 1 1 1 1 1 1 1 1  NB. 0s for vacant, 1s occupied
>>    board
>> 1 1 1 1 1 0 1 1 1 1 1 1 1 1 1
>>    move =: 0 2 5
>>    move
>> 0 2 5
>>    board xor +./((1 0 0 0 0 0 0 0 0 0 0 0 0 0 0) |.!.0~ 3 1 $ -) move
>> 0 1 0 1 1 1 1 1 1 1 1 1 1 1 1  NB. The desired result, a new board
>>    f =: ((1 0 0 0 0 0 0 0 0 0 0 0 0 0 0) |.!.0~ 3 1 $ -)
>>    f move
>> 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0
>> 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0
>> 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0
>>    +./f move
>> 1 0 1 0 0 1 0 0 0 0 0 0 0 0 0  NB. Move 0 2 5 expressed as 15 element
>> binary array
>>    board xor +./f move
>> 0 1 0 1 1 1 1 1 1 1 1 1 1 1 1  NB. Again, the desired result
>>    board                       NB. Both board and move unchanged
>> 1 1 1 1 1 0 1 1 1 1 1 1 1 1 1
>>    move
>> 0 2 5
>>    g =: xor +./
>>    make_move =: g f
>>    board make_move move
>> 0 1 0 1 1 1 1 1 1 1 1 1 1 1 1  NB. Again, the desired result
>>
>> ++++++++++++++++++++++++++++++++++
>>
>> The question: How to write make_move without creating subfunctions f and g?
>>
>> I've tried several definition variations and keep getting 'length error'
>> messages upon usage.
>>
>> One example:
>>    make_move =: xor+./((1 0 0 0 0 0 0 0 0 0 0 0 0 0 0) |.!.0~ 3 1 $ -)
>>    board make_move move
>> |length error: make_move
>> ----------------------------------------------------------------------
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