Remember, The need for private multiline functions?
http://www.jsoftware.com/pipermail/general/2006-April/026718.html
I have some fresh insight after looking at R example,
> open.account <- function(total) {
list(deposit = function(amount) {
if (amount <= 0) stop("Deposits must be positive!\n")
total <<- total + amount
cat(amount, "deposited. Your balance is", total, "\n\n")
}, withdraw = .... [TRUNCATED]
> ross <- open.account(100)
> ross$withdraw(30)
30 withdrawn. Your balance is 70
> ross$balance()
Your balance is 70
This pattern of declaring a family of functions or
a whole class within one function is common for many
scripting languages, such as JavaScript, and is sometimes
favored for compactness and reduction name/objects clutter over
even existing more traditional alternatives of separate definitions.
The previous thread quickly became boring with variantions
of the adverb theme. So here's what I think a different
more natural looking approach: transformational (Chomskyan). It roots
from experience with JHP and SQLite. The undercurrent for it
is the distinction between most other (semi)interpretive
languages (JavaScript, Python, Ruby, SmallTalk) which use
a LISP based transitional form between text and execution
(the parse tree), and APL based languages such as J which go
directly from text to execution for expressions and explicit verbs
(or at least percieved as such, see end of message *).
So instead of transforming the parse tree, the text of
the definition can be manipulated.
For an example of injecting prolog and epilog code text
around verbs see
D:\Math\j601\addons\jhp\examples\phrasedb\phrdb.ijs
where the new compact definitions looks like
getGroups=: verb sdefine
r=. query__db sqlGroups
)
and a try/catch with error handling is injected for "sdefine".
In JHP the whole .jhp page definition becomes a single
verb with verbatim static content injected as print
commands.
So the point is: why not use a similar textual transformation
to process the extended explicit definition format into
something acceptable by standard definition (3 : n).
For example,
BigVerb=: verb muldef
privC=. 2 : 0
privC sent1
privC sent2
)
privV=. 3 : 0
privV sentences
)
BigVerb stuff here...
)
into eqvivalent of
BigVerb=: 3 : 0
privC=. 2 : ('privC sent1';'privC sent2')
privV=. 3 : ('privV sentences';...)
BigVerb stuff here...
)
_______
* It turns out, explicit definitions can be manipulated similar
to LISP (executable) structures. Here we reassemble an explicit
definition using explicit representation. Obviously, transformations
are possible at this control-grained level.
v1=: 3 : ('if.y do.a=.123';'a+y end.')
{:"1]1 (5!:7)<'v1'
+---+-+---+------+---+----+
|if.|y|do.|a=.123|a+y|end.|
+---+-+---+------+---+----+
3 : ({:"1]1 (5!:7)<'v1')
3 : 0
if.
y
do.
a=.123
a+y
end.
)
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