HI Skip,
I see what you are saying. I assume you can't put constants in a tacit
expression as follows:.
d1 =: ([: +/([ - ]) ^ 2) ^ 0.5
Why is this? I can understand why named nouns aren't allowed, but not
why constants aren't.
Don
----- Original Message -----
From: "Kip Murray" <[email protected]>
To: "Chat forum" <[email protected]>
Sent: Wednesday, April 29, 2009 1:55 AM
Subject: Re: [Jchat] Language S
> Don Watson wrote:
>
>> The grammar of tacit S is identical to the grammar of explicit J ...
>
>
> You can come close to S with J's tacit programming
> --------------------------------------------------
>
> Here are three verbs for the distance formula, distance is (Sum of
> (x-y)^2) ^ 0.5
>
> d =: 4 : '(+/(x-y)^2)^0.5'
>
> d1 =: ([: +/([ - ]) ^ 2"_) ^ 0.5"_
>
> d2 =: ([: +/ - ^ 2"_) ^ 0.5"_
>
> p =: 1 2
>
> q =: 4 6
>
> p (d,d1,d2) q NB. Distance from p to q three ways
> 5 5 5
>
>
> Explicit verb d is a straightforward transcription of the algebraic
> formula.
>
> Tacit verb d1 is a recognizable transcription of the explicit once you
> know [: f g means "the f
> of g" and 2"_ and 0.5"_ are constant functions -- for every x and y, 2"_ y
> is 2 and x 2"_ y is 2.
>
> My point is, verb d1 is fairly close to the way Don Watson's S would
> express it: you can come
> close to S with J's tacit programming.
>
> Tacit verb d2 is less recognizable because unneeded left and right
> identity functions have been
> removed.
>
>
> Learning to appreciate trains
> -----------------------------
>
> A train f g h i j (in which the letters represent verbs) can be visualized
> as a binary tree
> created from right to left
>
> g
> / \
> f i
> / \
> h j
>
> The application (f g h i j) y means right argument y is supplied at each
> terminal node f, h, j,
> and the application x (f g h i j) y means left and right arguments x and y
> are supplied at each
> terminal node. Thus
>
> (f g h i j) y means (f y) g (h y) i (j y)
>
> and
>
> x (f g h i j) y means (x f y) g (x h y) i (x j y).
>
>
> A left terminal node may be [: (cap), in which case no argument is
> supplied there, and the
> parent node is applied monadically to the result of the right node. Thus
>
> (f g [: i j) y means (f y) g (i j y),
>
> x (f g [: i j) y means (x f y) g (i x j y).
>
> Beginners should avoid trains in which a left terminal node is missing.
>
> A balanced tree can be accomplished with parentheses:
> train (u f v) g h i j is
>
> g
> / \
> f i
> / \ / \
> u v h j
>
>
> Kip Murray
>
--------------------------------------------------------------------------------
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
