Re: Does Codd's view of a relational database differ from that ofDate&Darwin?[M.Gittens]
Date: Thu, 23 Jun 2005 06:15:24 GMT
> "Jan Hidders" <jan.hidders_at_REMOVETHIS.pandora.be> wrote in message
>>>But let's not sidetrack to XQuery, rather tell me what 'print' is in >>>Daplex without drawing analogies with XQuery. Just give a definition >>>if you please. >> >>The identity function. The print is only there to indicate that you >>produce a value, so you can simply translate it to the expression that >>produces that value if you makes sure that they are concatenated for each >>value that you iterate over.
> I do not understand this. I tried different interpretation but none fits.
> The closest translation might be:
> "' for each' denotes a list comprehension; 'print' is a monadic unit
> (identity ?) presumably applied to the constructed list. Is that so ? Or
> you meant something different by 'identity' ?
The expression "for each x in e1 print e2" denotes "[ e2 | x <- e1 ]". Why do you think that apart from this there is some need to give a separate definition of "what print is in DAPLEX"?
- Jan Hidders