What does "as fundamental as function composition" mean here? The article just appears to describe transducers. Transducers <i>compose</i> via ("reverse") function composition, sure, but that just means that they <i>are</i> functions of a type... and considerably less fundamental than <i>functions</i> since they're a specialization of that class of things.<p>They're cool and all—I've characterized them (partially, perhaps) as CPS encoded flatmaps over lists and also as stateful left fold transformers, the latter of which being much more general—but they're more like a rich ecosystem for list transformations than any kind of <i>fundamental</i> abstraction.
Title shows author doesn't understand programming language design. No, a small set of higher-order functions[1] is not as fundamental as the concept of higher-order functions in the first place.<p>[1]: <a href="http://www.reddit.com/r/haskell/comments/2cv6l4/clojures_transducers_are_perverse_lenses/cjjgbbs?context=3" rel="nofollow">http://www.reddit.com/r/haskell/comments/2cv6l4/clojures_tra...</a>
If you ignore the arities, ignore the internal state, and correctly observe the unwritten rules, yes transducers act like function composition. I looked into this here: <a href="http://www.colourcoding.net/blog/archive/2014/08/16/lets-write-a-transducer.aspx" rel="nofollow">http://www.colourcoding.net/blog/archive/2014/08/16/lets-wri...</a><p>I think Rich's innovation here is extremely clever and quite subtle, but it's pretty Clojure-specific, both in terms of the problem it solves and the way it solves it.
Subset of high-order functions are more fundamental than operations defined for a whole set?)<p>Clojure's are more fundamental than other languages?
What is the difference (or what is gained) from transducing a reducer over mapping (filtering, etc) a list and reducing it? Is it a clojure-specific optimisation?
In addition to map transducers (which are 1-to-1) and filter transducers (which are many-to-1), flatMap transducers (which are 1-to-many) should be fundamental.