Hello, On Sun 22 May 2011 19:43, John Cowan <cowan@mercury.ccil.org> writes: > My original view of blobs was as something that didn't have a native > structure, but was just raw binary data. That's why I proposed the > name "blob" rather than "byte/octet vector", which would imply a native > structure of octets. In my view, blobs could be seen as octets, but > equally well as 32-bit words in network (big-endian) order, or double > complex numbers, or UTF-8 strings. All these interpretations are equal > in BlobAPI. This is all fine to me. For example this is what Guile does: you can access bytevectors with the SRFI-4 accessors. There is a type bit saying what the default interpretation should be, which is useful for printing, for example. But you can do (bytevector-u16-ref (u32vector 0) 2 (endianness little)), and you get 0. > For blobs in full generality, though, blob-map would make no sense > because there was no unique element type for it to map over. A fair point. However I still fail to get the difference relative to R6RS bytevectors; e.g. you don't have bytevector-ref, it's bytevector-u8-ref. So you could have bytevector-u8-map, the same as blob-u8-map -- not that I think that's a useful operation of course ;-). > So somehow the mental model issue has to be resolved, after which these > details will just fall out naturally. If blobs are really u8 vectors > and everything else is just an overlay, then blob-map, blob-for-each, > etc. make sense. If all views of blobs are cognitively equal (which > is how I really think), then they don't, and the restriction to a u8 > setter/getter is just to keep WG1 small. It is a leaky abstraction, I think. For any unit which is not one byte in length, you always have to be concerned about the size of the total array. There's no way to treat (make-blob 5) as an array of u32 values. How would a blob not be interpretable an array of bytes? It is implicit in the type of `make-blob' that it's a bytes thing. Andy -- http://wingolog.org/ _______________________________________________ Scheme-reports mailing list Scheme-reports@scheme-reports.org http://lists.scheme-reports.org/cgi-bin/mailman/listinfo/scheme-reports
