Hi, In Gambit 4.7.2 documentation, in the section dedicated to threads, there is the following code example :
(define thread-alive? (let ((unique (list ’unique)))
(lambda (thread) ; Note: this procedure raises an exception if ; the thread terminated abnormally. (eq? (thread-join! thread 0 unique) unique))))This code is actually incorrect (according to gsi), the let is rejected. I believe that :(define thread-alive? (lambda (thread) (eq? (thread-join! thread 0 'unique) 'unique))) should be enough (though I do not know what happens if the thread returns nothing). I would like to know if there was some precise reason behind this let construction.Thanks, Denis
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Denis, the unique variable is for it to work even if the thread ended its execution by returning a symbol by the name unique - it interprets fine, what's your err?
2014-05-12 2:38 GMT+02:00 Denis Fourt denis.prog@hotmail.com:
Hi,
In Gambit 4.7.2 documentation, in the section dedicated to threads, there is the following code example :
(define thread-alive? (let ((unique (list 'unique)))
(lambda (thread) ; Note: this procedure raises an exception if ; the thread terminated abnormally. (eq? (thread-join! thread 0 unique) unique))))This code is actually incorrect (according to gsi), the let is rejected. I believe that :
(define thread-alive?
(lambda (thread)
(eq? (thread-join! thread 0 'unique) 'unique)))should be enough (though I do not know what happens if the thread returns nothing). I would like to know if there was some precise reason behind this let construction.
Thanks,
Denis
Gambit-list mailing list Gambit-list@iro.umontreal.ca https://webmail.iro.umontreal.ca/mailman/listinfo/gambit-list
Hi, my error was that the "quote" was actually a different unicode char (from the copy/paste), therefore gsi did not understand it as a quoted symbol but as an unquoted (undefined) symbol. And I got a weird error message because of the code point of that char was written right in it. And I have to admit it, I had no clue about what was occurring. I understand that no thread could return anything that would be eq? with (let ((unique (list 'unique))). But : a) Is there anything more simple than using list? b) Would it be a good idea to have one (or more) reserved symbol (or keyword) in Gambit like None, Nothing, Fail, etc. to handle that kind of problem. I am asking this question because a similar problem arises with hash table or similar dictionary like structures. Most of the time #f or '() work except when storing booleans or lists. Any thoughts? Denis
From: mikael.rcv@gmail.com Date: Mon, 12 May 2014 14:33:44 +0200 Subject: Re: [gambit-list] example from the doc To: denis.prog@hotmail.com; gambit-list@iro.umontreal.ca
Denis, the unique variable is for it to work even if the thread ended its execution by returning a symbol by the name unique - it interprets fine, what's your err?
2014-05-12 2:38 GMT+02:00 Denis Fourt denis.prog@hotmail.com:
Hi, In Gambit 4.7.2 documentation, in the section dedicated to threads, there is the following code example :
(define thread-alive? (let ((unique (list ’unique)))
(lambda (thread) ; Note: this procedure raises an exception if ; the thread terminated abnormally. (eq? (thread-join! thread 0 unique) unique))))This code is actually incorrect (according to gsi), the let is rejected. I believe that :(define thread-alive? (lambda (thread) (eq? (thread-join! thread 0 'unique) 'unique)))
should be enough (though I do not know what happens if the thread returns nothing). I would like to know if there was some precise reason behind this let construction.
Thanks, Denis
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2014-05-12 19:55 GMT+02:00 Denis Fourt denis.prog@hotmail.com:
Hi,
my error was that the "quote" was actually a different unicode char (from the copy/paste), therefore gsi did not understand it as a quoted symbol but as an unquoted (undefined) symbol.
And I got a weird error message because of the code point of that char was written right in it. And I have to admit it, I had no clue about what was occurring.
I understand that no thread could return anything that would be eq? with (let ((unique (list 'unique))). But :
a) Is there anything more simple than using list?
Uninterned sy.
b) Would it be a good idea to have one (or more) reserved symbol (or
keyword) in Gambit like None, Nothing, Fail, etc. to handle that kind of problem. I am asking this question because a similar problem arises with hash table or similar dictionary like structures. Most of the time #f or '() work except when storing booleans or lists.
No just use a unique object for this purpose - if there'd be a global undefined value, then of course you'd get the same uniqueness problems with it as with a global symbol like 'undefined , or #f etc.
Any thoughts?
Denis
From: mikael.rcv@gmail.com Date: Mon, 12 May 2014 14:33:44 +0200 Subject: Re: [gambit-list] example from the doc To: denis.prog@hotmail.com; gambit-list@iro.umontreal.ca
Denis, the unique variable is for it to work even if the thread ended its execution by returning a symbol by the name unique - it interprets fine, what's your err?
2014-05-12 2:38 GMT+02:00 Denis Fourt denis.prog@hotmail.com:
Hi,
In Gambit 4.7.2 documentation, in the section dedicated to threads, there is the following code example :
(define thread-alive? (let ((unique (list 'unique)))
(lambda (thread) ; Note: this procedure raises an exception if ; the thread terminated abnormally. (eq? (thread-join! thread 0 unique) unique))))This code is actually incorrect (according to gsi), the let is rejected. I believe that :
(define thread-alive?
(lambda (thread)
(eq? (thread-join! thread 0 'unique) 'unique)))should be enough (though I do not know what happens if the thread returns nothing). I would like to know if there was some precise reason behind this let construction.
Thanks,
Denis
Gambit-list mailing list Gambit-list@iro.umontreal.ca https://webmail.iro.umontreal.ca/mailman/listinfo/gambit-list
Gambit-list mailing list Gambit-list@iro.umontreal.ca https://webmail.iro.umontreal.ca/mailman/listinfo/gambit-list
On May 12, 2014, at 1:55 PM, Denis Fourt denis.prog@hotmail.com wrote:
Hi,
my error was that the "quote" was actually a different unicode char (from the copy/paste), therefore gsi did not understand it as a quoted symbol but as an unquoted (undefined) symbol.
Ah yes! Copy pasting Scheme code from the PDF manual is not a good idea, in particular because the single quote character is replaced by latex by a different quote (perhaps because it looks better, i.e. more slanted).
It seems to be fine to copy/paster from the HTML manual though.
Marc
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Denis Fourt -
Marc Feeley -
Mikael