On Jun 14, 10:09 pm, Jared <tri...@gmail.com> wrote: > Also, I thought this language is functional but I'm able to do change > declarations in the repl. For example: > user=> (def x 1) > #'user/x > user=> x > 1 > user=> (def x 2) > #'user/x > user=> x > 2 > user=> (def x (+ 1 x)) > #'user/x > user=> x > 3 > > Why does that happen? This seems to go against the ideas of functional > programming. I can do the same things with functions too.
It's true that def isn't a strictly functional construct. That's by design, since def is the construct that allows you to define and set globally accessible vars, which includes all globally accessible functions. If you couldn't re-def a var, you couldn't redefine functions while coding (or modify/extent existing functions using macros etc). Clojure (like most Lisps) is a dynamic language with strong support for interactive development - and you need redefineable vars (or something similar) for that. The alternative is to recompile/load the whole program every time you change a function definition. And that sucks too much. In idiomatic code, you only use (def) and its variants to set up globally reachable data/functions across all threads and you don't, for example, use def as a way to get "variable variables" - you will get bitten if you try. -- 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
