Yves Pare`s wrote:
I cannot help smiling when I hear Java/C#/Python developers telling about the "wondeful features" of their languages ;) (- We have generators! We can _yield_ values! [1] - Yeah, so nice... We have simple lists... with lazy evaluation)
Just for the record, lazy lists per se are sufficient only for simplest generators. Re-writing an accumulating traversal to accommodate suspension by hand is too ungainly and error prone. Still, if we just add exceptions (the Either monad), we can idiomatically write all the generator examples of Python or Icon, for example. If we do not need effects other than yielding or non-determinism, [Either e a], which is ErrorT e [] a, suffices. If we need IO or mutable state, we should replace [] with LogicT (which is the monad of lazy lists with effect). The following web page talks about lazy lists and generators http://okmij.org/ftp/continuations/generators.html in (perhaps too) great detail.