There is another solution.
Make your noun into a verb as in:
NB. just a few helpers, could be defined later.
pathA =: [: (|. each) (;~ 0$0) , (<\@:+ i.) NB. calculation of the data
pathB =: <\ i. NB. Either monadic or dyadic hook, possible
pathC =: (2 pathA 7)"_ NB. Set the noun into a verb
NB. Define your verb, this definition doesn't change
NB. At this point "paths" must be either undefined or a verb!
g =. >@{ paths NB. This is now a hook
NB. we specify what the paths are that verb g is to use.
paths =: 2 pathA 7: NB. This constant verb (fork) corresponds
NB. to your first example data
g 4
g 3 2 $ 2 4 1 5 0
g 8
paths =: pathC NB. This also corresponds
NB. to your first example data
g 4
g 3 2 $ 2 4 1 5 0
g 8
paths =: 3 pathB 16"_ NB. Another constant verb (also a fork)
g 4
g 3 2 $ 2 4 1 5 0
g 8
paths =: _3 pathB 16"_ NB. Another constant verb (also a fork)
g 4
g 3 2 $ 2 4 1 5 0
g 8 NB. gives an error!
Ian
Ian Shannon
Landscape Modelling & Decision Support
Scientific Services
Office of Environment and Heritage
Department of Premier and Cabinet
PO Box A290
Sydney South
NSW 1232
T: +61 2 99 955 490
E: [email protected]
-----Original Message-----
On Jul 22, 2012 1:32 PM, "David Vaughan" <[email protected]> wrote:
> I have a noun called paths, whose value changes at various points, and a
> verb g that uses paths. The problem is, it only works for the initial value
> of paths.
>
> paths =: \:~&.> (;~ 0$0) , <\ 2+i.7
> paths
>
>
> g =. >@{&paths
> g
> @{&((0$0);(0$0);(,2);3 2;4 3 2;5 4 3 2;6 5 4 3 2;7 6 5 4 3 2;8 7 6 5 4 3 2)
>
> So now when paths changes, g becomes useless.
>
> My question is how can I get g to always check the value of paths when it
> is executed? And more generally, how can the name of a noun rather than the
> value of the noun be used in a verb?
>
> Many thanks.
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