[Swift-devel] Re: [Newslab] Re: Getting all RSS data into database

[Ben Clifford]

Note: I added swift-devel to this piece of the thread because it is 
relevant there; and perhaps now not so relevant to the newslab list.

On Tue, 26 Feb 2008, Quan Tran Pham wrote:

> > What I think you are trying to do is merge a bunch of files into a single
> big file? (which is not in itself a merge sort)

> I have merge2 that merge two sorted files (contain sorted key + value) into
> one big sorted file.

A different way of thinking about this, which is perhaps more of interest 
to the swift development group rather than newslab directly:

Define a binary operator like >+ meaning somthing like 
ordered-concatenate, which will combine two files in the appropriate 
ordered fashion.

  file >+ file  -->  file

This operator is commutative.

Then have foldC able to fold knowing that the supplied operator is 
commutative (so it can split up in a binary fashion, or however other way 
it cares to).

Now say:

  file[] inputs 
  file output
  output = foldC (>+) inputs

Perhaps foldC should be provided by Swift, with >+ provided as a 
procedure.

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