2016-11-20 11:42 GMT+01:00 Jan Synáček <jan.syna...@gmail.com>: > > >> Please, tell me that this is just a mistake... This can't be true. I > >> still can't believe it. This is from 2.0.11. Please, tell me that the > >> implementation is fixed in 2.2. > >> > >> Yours truly puzzled, > > > > > > I don't know why you find it so puzzling. You can't take or drop > something > > that "isn't there" (you can't take a car or cdr from an empty list as > well, > > although e.g. in the language of "The Little Prover" (car '()) and (cdr > '()) > > both evaluate to '() to assure their totality). If you need, you can > define > > your own variants that take/drop at most n elements of list. > > Not only that you "can", it's also IMHO a fool-proof implementation > and I can't see any reason why it should behave differently. >
Because someone might think that if he took 7 elements, then he has 7 elements, so it is good that he knows earlier that this is not the case. I don't see a point in referring to Haskell documentation when discussing Scheme functions, though (if you try Racket, you'll note that although its take has a reversed order of arguments compared to srfi-1, it still doesn't allow to take or drop a positive number of elements from an empty list) I agree though that the srfi-1 document isn't explicit enough about this point.
