Hi. I'm learning Clojure, and I like a lot what I've seen so far. Thank you Rich for designing such a nice langage, and Stuart for writing such a great book!
I'm a little worried about the pattern matching/destructuring binding feature though. It looks very powerful, but also very dangerous. It seems to encourage people to "peek inside" the internals of structured values with no restrictions. The kind of scenario I'm worrying about is this: - Alice writes library foo and use a particular way to encode values (say simple vectors). She publishes foo v1.0. - Bob starts using foo, and because it is so simple and convenient, uses desctucturing everywhere. - Alice adds new features to version 1.1 her library, realizes the simple vectors are not enough and decides to use hashmaps instead. - Bob updates to version 1.1 of foo, and some of his code starts to break, because all the patterns he's used are now obsolete. He has no other solution than to audit all his code to locate (not necessarily a trivial task) and update the destructuring patterns which concern foo data. Basically the only way I see to avoid this is for Alice to consider her choices in encoding part of the published API of the library, and commit to never change it after initial publication, which is rather too restrictive. I understand that the problem would exist even without destructuring bindings, but from reading Stuart's book, it seems their use is encouraged and considered good style. Coming from an OO background which puts a strong focus on data encapsulation, this makes me a little nervous. Languages like Haskell also have pattern matching, but from what I understand, because they are strongly and statically typed, incompatible changes are detected at compile time so they can easily be found and fixed. Am I worrying for nothing? I have not yet written anything serious in Clojure so perhaps these problems do not occur in practice. Maybe following some simple guidelines are enough to avoid problems? --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~----------~----~----~----~------~----~------~--~---
