An additional comment. see below. /Erling
On 2017-09-29 04:45, Henry Rich wrote:
Taking your last sentence first, you would have to supply some
evidence to make me believe that tacit forms have any intrinsic
performance penalty.
It is dawning on me that you want fast function definition, but that
you want it to produce tacit code. You find the current tacit
language difficult, and you propose to replace it with something that
looks more like the explicit language. That seems like a mistake to
me, because:
1. Most of the responders on this Forum don't agree with you that the
tacit language is opaque
2. Even with a fast function definition, many J programmers (I dare
not say all J programmers with a soul) will always prefer (+ i.) to (.
x + i. y).
This is a strange comparison, (+ i.) is comparable to + i. with explicit
syntax. [ ( + i. ) ] is comparable to x + i. y and ([ (+ i.) ]) is
comparable to (. x + i. y).
3. Tacit code is a different mindset from explicit code. It's
functional. It doesn't have assignments or control words
4. Operands to modifiers cannot be arguments to tacit code
5. Explicit syntax is an improvement in some cases, not all. +/ *: y
is a little lighter than +/@:* y but (+/ y) % #y is heavier than (+/ %
#) y
6. So: even if I were redesigning the language from scratch, I
wouldn't represent tacit forms your way. I would, as Roger has
observed, switch the meanings of (u v) and (u@:v), but I would keep
the rest as is.
[Note for those who have not been using J for more than 10 years: the
original tacit language allowed trains that produced modifiers. That
was, to me, Ken's finest achievement: a really beautiful language,
immensely supple, even though it had no syntactic elements but the
primitives and parentheses. I never found it wanting. It was fully
understood by no more than half a dozen people, I think. It was
removed from J because explicit forms could produce the same results:
a good business decision, but a loss to computer science and art.]
7. The bottom line: tacit forms work pretty well as they are, and an
incompatible change to them could be justified only by a huge
improvement in readability or efficiency. You haven't shown that.
Henry Rich
On 9/28/2017 10:09 PM, Erling Hellenäs wrote:
Hi all !
Is improving explicit J the way forward? Or is tacit J and improving
tacit J the way forward?
I also think that "Henry's" proposal, which is similar to what I have
been writing about for a long time, is great. It is easy to do and
have great benefits for people working in explicit J. They will not
have to type lots of double quotes, or write their own J versions
with special duplicate quote functionality.
That doesn't mean that tacit J could not also be improved?
Henry's proposal is nearly identical to my proposal but mine is about
tacit J, it is addressing problems with tacit J. His is about
explicit J. It is addressing problems with explicit J, the quote
duplication problem. I am addressing problems with tacit J, mainly
the problem which makes people write cross-compilers from explicit to
tacit J or programs to automatically pack verb sequences in tacit J
into their packages of brackets and phony "compositors", like this -
f@:(g@:(h@:(i@:(j@:])))). People who are working professionally with
tacit J and who knows that cheating and writing tacit J like most
other people do will slow their programs much too much?
Cheers,
Erling
On 2017-09-29 03:13, Joe Bogner wrote:
I also like Henry's suggestion of fast function definition. It's also
unclear to me on how the Erling's suggestion improves upon that.
On Thu, Sep 28, 2017 at 5:45 PM, Louis de Forcrand
<[email protected]> wrote:
I don't really understand what you wish to add either, Erling.
If you want to use explicit J syntax, you could write an explicit
verb.
You write:
Particularly to create what you most commonly need, a sequence of
monadic verbs, each acting on the result of the verb to the right.
Well, it is not complicated as such, but for some reason people don't
like
the obvious way to do it, which is [: f [: g [: h ]. Then they
dive into
a
mess of complications. I mean the cap should not be necessary. That
simple
right to left execution should be the default, possibly modified with
parenthesis. That tacit and explicit J should have the same basic
syntax.
f@:g@:h?
In addition, I disagree with your last two sentences. What's the
point of
having tacit syntax if it's the same as explicit syntax? If you want
explicit syntax, write an explicit verb; other times tacit syntax
is really
practical.
In an explicit verb, simple right to left execution *is* the default.
In any case I don't really see how the rest of your suggestion differs
from Henry's (.). verbs, which I like very much by the way.
Cheers,
Louis
On 28 Sep 2017, at 14:53, Raul Miller <[email protected]> wrote:
Jose's work is impressive, but I try to avoid it because of the extra
complexity it creates when I want to (for example) provide a
parameter
in clauses for conjunctions like &. -- the extra complexity can be a
nice mental exercise and maybe even a cure for boredom, but I feel
that I have the right to treat it as unnecessary.
Thanks,
--
Raul
On Thu, Sep 28, 2017 at 8:33 AM, Erling Hellenäs
<[email protected]> wrote:
Hi all !
I am very impressed by Jose's work and I think it is an excellent
illustration to why we need the modification to J I propose.
It is extremely complicated to do these things which should be
simple,
as I
see it. Particularly to create what you most commonly need, a
sequence
of
monadic verbs, each acting on the result of the verb to the right.
Well, it is not complicated as such, but for some reason people
don't
like
the obvious way to do it, which is [: f [: g [: h ]. Then they dive
into a
mess of complications. I mean the cap should not be necessary. That
simple
right to left execution should be the default, possibly modified
with
parenthesis. That tacit and explicit J should have the same basic
syntax. I
tried my ideas of a different tacit J in a test implementation
and it
was
great.
Cheers,
Erling Hellenäs
On 2017-09-28 05:29, Jose Mario Quintana wrote:
Hi Erling,
You are right, the adverb (At) produces tacit sentences but it is
really
an
implementation of Dan's pipeline proposal using strand notation
via a
Curried adverb (aka, recurrent adverb and multiple adverb).
However, I have written (tacitly) a tacit Curried adverb (xi)
which,
using
a lambda-style syntax, produces a tacit verb which in turn,
given its
arguments, produces tacit entities. You might find xi
interesting; the
general form is,
t=. [: v0 v1 ... vn '...' xi
The names v0 v1 ... vn should be syntactically verbs (recall, xi
is a
Curried adverb) but they can represent nouns, verbs, adverbs, or
conjunctions. I use undefined names since those are regarded by
default
as
verbs (even if xi does not affect in any way the named verbs). The
literal
'...' represents a quoted J (or more generally a Jx) sentence.
This is how your example can be written using xi,
erase 'b v'
[: v '([: b ''<:b++/\b-~-.b'' xi <''\''=v){."0 v' xi
<'\\\//\\\//'
\
\
\
/
/
\
\
\
/
/
There is the nuisance of quotes within quotes and the argument
must be
boxed; however, this allows, in general, the verb (t) to produce a
noun, a
verb, an adverb, or a conjunction and to take multiple boxed nouns,
verbs,
adverbs, or conjunctions as its argument. The following verb
(t) acts
directly on a couple of (boxed) verbs and produces a verb,
t=. [: u v 'u/@:v' xi
t[:+*:]: NB. Sum of squares
+/@:*:
t[:+*:]: 1 2 3 4 5
55
t[:-%:]: NB. Difference of square roots
-/@:%:
t[:-%:]: 1 2 3 4 5
1.55390522
Note that the Curried higher-order verb (t) is, in effect,
acting on
two
arguments: [:-%:]: and 1 2 3 4 5; furthermore, t [:-%:]: performs a
partial
application of the verb (t) acting on [:-%:]: .
The following are variations of the verb produced in [0], the
verb (t)
acts on a (boxed) conjunction and produces an adverb,
t=. [: u '(ver adv u)&:train/adv' xi
]`{.`{:`{: (t [:(<adv@:)]:) NB. Use [:(<'@:')sb in J
]@:({.@:({:@:{:))
]`{.`{:`{: (t [:(<adv@ )]:) NB. Use [:(<'@ ')sb in J
]@({.@({:@{:))
]`{.`{:`{: (t [:(<adv&:)]:) NB. Use [:(<'&:')sb in J
]&:({.&:({:&:{:))
These non-compliant features are not provided by the Jx
interpreter;
they
are, in fact, inherited from the J interpreter, the Jx
facilities just
make
them a lot more accessible. Actually, I have written a version
(admittedly
cumbersome) of xi in J; see [1] for a link to a zip archive and the
path
to
a script where xi is defined.
PS.
erase'u0 u1 u2'
1 1 1
[: u0 u1 u2 'u0 + u1 + u2' xi 1 ; 2 ; 3
6
erase'α β γ'
1 1 1
[: u0 u1 u2 'u0 + u1 + u2' xi [:α β γ]:
α + β + γ
References
[0] [Jprogramming] Gerund composed application
http://www.jsoftware.com/pipermail/programming/2017-
September/048797.html
[1] J Wicked Toolkit
http://www.2bestsystems.com/foundation/j/Jx.zip
\Jx\J\J Wicked Toolkit.ijs
On Wed, Sep 27, 2017 at 5:10 AM, Erling Hellenäs
<[email protected]>
wrote:
Hi all !
Pascal, I will come back to your post later.
Here is a little compiler written in Jx and compiling, as I
understand
it,
tacit code with explicit J syntax into tacit J. I did not test
it, I
just
read the post.
http://www.jsoftware.com/pipermail/programming/2017-
August/048143.html
The code snippet Farey is an example of the source code of the
little
compiler.
I just think we should not have to use a tacit J compiler from
explicit J
to be able to use explicit J syntax and get a tacit result, a
single
verb.
It would obviously be better to use explicit J syntax in the first
place,
as i see it.
Cheers,
Erling
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