Re: [Bug-apl] Towards a keyed and component file system

[Blake McBride]

Blob support, in general, would be good, but I don't think it is a good solution to this problem.  I am thinking of converting all arrays to these strings.  I don't think databases are especially efficient if everything is a blob.  They handle strings much more efficiently.  I think the best solution would be to implement a 13⎕CR and 14⎕CR that would translate back and forth using only printable ASCII characters without any control characters, '\0', high bit, etc..  Would this be hard?

Thanks a lot!

Blake

On Sat, Apr 19, 2014 at 9:43 AM, Elias Mårtenson <address@hidden> wrote:

You are right. The SQL implementation uses C strings behind the scenes for both SQLite and Postgres.

I'll be happy to implement BLOB support if you can suggest a good syntax for it from APL.

Regards,

Elias

On 19 April 2014 22:34, Blake McBride <address@hidden> wrote:

Looks good.  I am a little concerned that the vector produced by 3 ⎕TF may have trouble going to and from an SQL VARCHAR using the existing (and fantastic!) library.  I am not sure, but there may be a problem with C null characters ('\0') or other non-printable characters.  Some feedback on this would be very helpful.

Thanks!

Blake

On Sat, Apr 19, 2014 at 9:20 AM, Juergen Sauermann <address@hidden> wrote:

Hi Blake,

I have added 11⎕CR for APL → CDR and 12⎕CR for CDR → APL conversions, see SVN 217.

For example:

      12 ⎕CR CDR←11 ⎕CR 'Hello' 1 (2 3)
 Hello 1  2 3
      ⍴CDR
128

/// Jürgen



On 04/19/2014 12:16 PM, Blake McBride wrote:

Greetings,

Now that the wonderful SQL interface is working for me, I believe I can create a component and keyed file system in straight APL easily.  I just need to understand ⎕TF a bit better.

1.  3 ⎕TF seems to produce a string vector representation of an arbitrary nested array without retaining the specific name of the variable.  Is this true?  (If so, this is exactly what I need!)  

2.  How can I reverse the process?  i.e. if X holds the result of a 3 ⎕TF, I need a way of converting it back to an APL (possibly nested) array that is exactly the same array.  i.e.:

x←(5 5⍴⍳25) 'Hello there'

y←3⎕TF'x'

z←??????????

I need to know what ?????? is so that x and z have the exactly equivalent arrays.

3.  I am a little concerned that the vector produced by 3 ⎕TF may have trouble going to and from an SQL VARCHAR using the existing (and fantastic!) library.  I am not sure, but there may be a problem with C null characters ('\0') or other non-printable characters.  Some feedback on this would be very helpful.

I suppose I can achieve the same effect by using 2⎕TF and then dropping the assignment part before executing the string.  This should be highly portable but I'd guess less efficient.  Thoughts?

Thanks a lot!!

Blake