Scalar languages have a need for non-mutable arrays. Array languages do not. As Bill said, all arrays in J are non-mutable. But names are not. As I understand it, the in-place operations are allowed only for actions that cannot fail part-way through leaving an array half-modified.
On Sun, Oct 2, 2016 at 5:13 AM, bill lam <[email protected]> wrote: > I think other forum members should have answer your question, > All J array are non-mutable. eg, an array 0 1 2 cannot becomes > 0 1 2 3 or 0 1. But value assigned to a name can change. > If you meant a name can only be assigned a value once, it was > called "given name" in ancient J, and was dropped long time ago. > I might not recall correctly, that was 2 or 3 decades ago. > > In-place operation is an implementation detail not a language > feature. > > Вс, 02 окт 2016, Erling Hellenäs написал(а): > > No - I wish I knew somewhere this is clearly described. What I think is > that > > in functional languages with non-mutable data we can avoid locking. > > Non-mutable data simplifies parallelization since the objects we work on > > never change. It enables massive parallelization without any locking > > schemes, I think. I hope someone in the forum can describe this better or > > link to some nice description. /Erling > > > > On 2016-10-01 23:28, Henry Rich wrote: > > > It sounds like you are conflating 'mutex' and 'mutable'. > > > > > > Henry Rich > > > > > > On 10/1/2016 4:15 PM, Erling Hellenäs wrote: > > > > I think non-mutable data is part of the solution to the locking > > > > problems in object-oriented languages. It seems there must be a > > > > limit after which even J has to use more than one thread? Is there a > > > > plan for how to handle that? Or are we using several threads > > > > already? /Erling > > > > > > > > On 2016-10-01 21:56, Erling Hellenäs wrote: > > > > > On 2016-10-01 15:40, 'Pascal Jasmin' via Programming wrote: > > > > > > Forcing immutable only arrays is not an option for this > > > > > > language if it is to remain compatible with itself > > > > > > > > > > Someone wants to give a more specific explanation to this? What > > > > > in the language prevents immutable only arrays? > > > > > > > > > > /Erling > > > > > > > > > > ------------------------------------------------------------ > ---------- > > > > > For information about J forums see http://www.jsoftware.com/ > forums.htm > > > > > > > > > > > > ------------------------------------------------------------ > ---------- > > > > For information about J forums see http://www.jsoftware.com/ > forums.htm > > > > > > ---------------------------------------------------------------------- > > > For information about J forums see http://www.jsoftware.com/forums.htm > > > > > > ---------------------------------------------------------------------- > > For information about J forums see http://www.jsoftware.com/forums.htm > > -- > regards, > ==================================================== > GPG key 1024D/4434BAB3 2008-08-24 > gpg --keyserver subkeys.pgp.net --recv-keys 4434BAB3 > gpg --keyserver subkeys.pgp.net --armor --export 4434BAB3 > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
