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On Mon, Aug 18, 2003 at 11:52:09AM -0700, oleg@xxxxxxxxx wrote: > > Hello! > > > procedure: *-get-left * [default]=> value > > > Returns an unspecified value from the given > > collection. If the collection is empty, default is > > returned if present, otherwise #f is returned. > > Hmm, "Returns an unspecified value". I know what you mean. However, > that word, 'unspecified', immediately reminded me a R5RS phrase "the > return value of the set! expression is unspecified". It isn't the same > unspecified, is it? Perhaps a phrase "Returns a value from the given > collection. For a general collection, it is unspecified which of its > values is returned. Ordered collection specify that." might be more > suitable. I agree. > > procedure: dict? value => boolean > > Returns a non-false value if the provided value is a flexible > > sequence > > You probably meant "dictionary" rather than a "flexible sequence". > Yep. > I also have a half-hearted suggestion about dictionaries. > collection-fold-left on dictionaries iterates on > values. collection-fold-keys-left iterates on keys. Somehow there > isn't anything that iterates on keys and the corresponding values. At > the first blush, keys+values seem to be a bit more useful than merely > values. Furthermore, it's usually quite easy for a collection to > obtain the corresponding key when iterating over values. OTH, > iterating on keys and using dict-get to get the corresponding value is > usually far less efficient. I thought that perhaps > collection-fold-left can pass to its fold-function not merely a value > but a pair (key . value). This is just a remark. It could, but that might impede passing dictionaries as ordinary collections to routines. Take for example a program which stores its data in a dictionary in order to provide quick access using a key to a single value, but wants to pass that dictionary as a blob of values to some function that is written to accept any collection. Passing keys+values to the proc in a collection-fold-keys-* should be fine however. CCing to the discussion list. Thanks, Scott
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