Re: get the 'up value of a variable across a lambda

[polifemo]

Ok, I see my mistake. I assumed that let and the rest could create
enclosing environments, when only a function call can.

Another example I made of how to use 'up:

: (de f () (and 1000 (up 1 @) @))
-> f
: (and 10 (f))
-> 10

Thanks for the clarification alex!

On Mon, May 24, 2021 at 12:55 AM Alexander Burger 
wrote:

> On Sun, May 23, 2021 at 08:44:32PM -0500, polifemo wrote:
> > `(let @ 1 (let @ 10 (let @ 20 (up 2 @`
>
> This are two misunderstandings in this example:
>
> 1. It has not a good idea to bind '@' in a 'let' expression. '@' is set
>implicitly by flow- and logic-functions, so a correct usage would be
>
>   (and 1 (or 10 (while 20 (up 2 @
>
>or - more realistically -
>
>   (and (foo) (or (bar) (while (zup) (up 2 @
>
> 2. 'up' does not care about 'let', 'use', 'for' etc. They are ignored. An
> up
>"enclosing environment" always means the enclosing *function*
> environment. So
>all the above 'let's all run in the same environment. The same rule
> applies
>to the environment offsets to 'eval' and 'run'.
>
>
> > returns 1, as I expected, if I enclose the 'up expression inside a
> function
>
> This return value of '1' just happens because the environment setup in
> bindeng
> '@' in 'let' is undefined.
>
>
> Let me try to give an example.
>
>(when 7  # The result of 'when' is what we are interested in
>   (extract
>  '((N)  # Here we are in a function
> (when (num? N)  # 'when' sets '@'
>(+ N @) ) )  # so we add the wrong '@'
>  (1 a 2 b 3)))
>-> (2 4 6)
>
>(when 7
>   (extract
>  '((N)  # in a function
> (when (num? N)
>(+ N (up 1 @)) ) )  # Here we get the '7'
>  (1 a 2 b 3)))
>-> (8 9 10)
>
> ☺/ A!ex
>
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>

Re: get the 'up value of a variable across a lambda

[Alexander Burger]

On Sun, May 23, 2021 at 08:44:32PM -0500, polifemo wrote:
> `(let @ 1 (let @ 10 (let @ 20 (up 2 @`

This are two misunderstandings in this example:

1. It has not a good idea to bind '@' in a 'let' expression. '@' is set
   implicitly by flow- and logic-functions, so a correct usage would be

  (and 1 (or 10 (while 20 (up 2 @

   or - more realistically -

  (and (foo) (or (bar) (while (zup) (up 2 @

2. 'up' does not care about 'let', 'use', 'for' etc. They are ignored. An up
   "enclosing environment" always means the enclosing *function* environment. So
   all the above 'let's all run in the same environment. The same rule applies
   to the environment offsets to 'eval' and 'run'.


> returns 1, as I expected, if I enclose the 'up expression inside a function

This return value of '1' just happens because the environment setup in bindeng
'@' in 'let' is undefined.


Let me try to give an example.

   (when 7  # The result of 'when' is what we are interested in
  (extract
 '((N)  # Here we are in a function
(when (num? N)  # 'when' sets '@'
   (+ N @) ) )  # so we add the wrong '@'
 (1 a 2 b 3)))
   -> (2 4 6)

   (when 7
  (extract
 '((N)  # in a function
(when (num? N)
   (+ N (up 1 @)) ) )  # Here we get the '7'
 (1 a 2 b 3)))
   -> (8 9 10)

☺/ A!ex

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Re: get function for chart holding list of db objects

[Alexander Burger]

Hi Olaf,

you are quite close, I think.

The 'keyA' relation has a small problem

 (class +Foo +Entity)
 (rel keyA (+Ref +Number) 2)
 (rel keyB (+Ref +String))

'+Ref' takes an optional argument, and '2' should be for '+Number',
so correct would be

   (rel keyA (+Ref +Number) NIL 2)


Then, instead of using Pilog

 (solve '( @F Floor
 @C Ceil
 (db keyA (@F . @C) @FooObj) )
 @FooObj) )

you could also simply (collect 'keyA '+Foo) to get a list of
all objects.

Note, however, that both 'solve' and 'collect' are not so wise if the
database has many '+Foo' objects, because they return _all_ objects and
thus the chart may become huge.

For displaying a possibly infinite number of objects in a chart, it is
better to use '+QueryChart' which displays just the first page of hits
and then lets you scroll down as far as you like. Examples for
+QueryChart can be found in doc/family.l and app/gui.l.


Besides this, your approach

 (gui '(+Init +Chart) (getFooObjs 5 100) 3

is not bad or wrong at all. However, the '+Lock' prefixes in

   (gui 1 '(+Lock +NumField) 10)

make the fields non-editable.

Thus,I would try something like

   (gui '(+Init +Chart) (collect 'keyA '+Foo) 2
  '((This) (list (: keyA) (: keyB)))
  '((L D)
 (when D
(put! D 'keyA (car L))
(put! D 'keyB (cadr L))
D ) ) )
   (table NIL NIL
  '((NIL KeyA) (NIL KeyB))
 (do 8
(row NIL
   (gui 1 '(+NumField) 10)
   (gui 2 '(+TextField) 10) ) ) )
   (scroll 8 T)

♪♫ Alex
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