I agree Robert, symbols are a logical fit if hash tables are implemented.
Symbols are a regular part of my diet (small size and quick checking of equality). The closest need to hash tables I have come across is looking up data in a table where one column is a symbol. Usually I look-up many items in one go, so overheads are not an issue and arrays are fine. De : 'robert therriault' via Programming <[email protected]> À : programming <[email protected]> Sujet : Re: [Jprogramming] Hashing primitives WAS: Farewell for now! Date : 14/04/2021 17:10:08 Europe/Paris I don't want to create unnecessary noise, but where could symbols fit into this? I have never been clear on their function within the language and so I have not used them. I do know that they also involve hash table look up. Is it possible to provide some verbs that can manipulate the Global Symbol Table? Cheers, bob > On Apr 14, 2021, at 07:56, Henry Rich <[email protected]> wrote: > > Let's get a spec for what we need before we implement. > > 1. What datatypes are needed? > * Dictionary > > 2. What operations are needed? > * Add key/value pairs > * return value for a given key > > 3. What are the types of key and value? > * they can have any type > * perhaps the keys have to have all the same type, values likewise > > Please fill this out. This is as far as I got, and for that I think the > Dictionary type could just be a numbered locale with a few methods. > > Henry Rich > > > > On 4/14/2021 10:47 AM, Raul Miller wrote: >> Conceptually, here, you're probably thinking about using hashes of >> character strings as array indices. >> >> A character string, in J, is either a boxed rank 1 list of characters >> or a rank 1 member of a higher dimensional character array which has >> been padded on the right hand side with spaces. >> >> Since all of the current array index primitives throw an error when we >> try to use characters to index them, I think that we would not need >> any new primitives -- we would "only" need to characterize the >> normalization process used to convert arbitrary character arrays or >> boxed character arrays to array indices. >> >> That said, these hashed arrays would also be sparse. And, it would be >> desirable to support boxed items and boxed hashes. And that gets into >> some issues which are ... rather involved, if we think about the >> existing sparse array implementation. >> >> So ... when estimating this task it might be best to think of it as >> "re-implementing sparse arrays from the ground up"? >> >> Thanks, >> > > > -- > This email has been checked for viruses by AVG. > https://www.avg.com > > ---------------------------------------------------------------------- > 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
