Specter – Clojure API for immutable programming (2017)

Specter is tremendously useful and rarely lets on a case where it can’t perform a transformation. For ensuring that you’re getting the most efficient form of a transformation [0] it’s incredible —- and it is somewhat data-oriented, allowing easy saving and reuse of navigators. Meander [1] is also wonderful. Its unification-based approach makes for nice expressions of intent. Its strategy-based approach to rewriting [2] is more flexible than most common walker libraries, too. [0]…

As one can see in two other top-level comments in this thread, the choice of an all-caps DSL is off-putting. It would be more idiomatic to have a hiccup-like API, where data is passed - not code, not syntax. And the keywords should be namespaced, so meaning is self-documented (and one gets superior IDE support).

This was the transformation that hooked me: (transform (subselect ALL :a even?) reverse [{:a 1} {:a 2 :b 1} {:a 4} {:a 5} {:a 6} {:a 8}]) ;; => [{:a 1} {:a 8 :b 1} {:a 6} {:a 5} {:a 4} {:a 2}]] I'm solid with Clojure, and I am not even sure how to begin expressing this transformation without Specter. Granted, it's not clear why you would want to do this in a real program. But I'm convinced about…