X y) (meta x) (meta y)]) ;=> [true fake {:ornery actual} {:ornery false}] the 2 locals x and y either carry an equivalent image 'goat, yet they’re various circumstances, each one containing separate metadata maps received with the meta functionality. the consequences of this are that image equality isn’t depending on metadata or identification. This equality semantic isn’t constrained to symbols, yet is pervasive in Clojure, as we’ll exhibit all through this booklet. You’ll locate that key words can’t carry metadata6 simply because any both named key-phrase is similar item. four. four. 2 Symbols and namespaces Like key phrases, symbols don’t belong to any particular namespace. Take, for instance, the next code: (ns where-is) (def a-symbol 'where-am-i) a-symbol ;=> where-am-i (resolve 'a-symbol) ;=> #'where-is/a-symbol `a-symbol ;=> where-is/a-symbol 6 Java category circumstances, together with strings, can’t carry metadata both. seventy two bankruptcy four On scalars The preliminary evaluate of a-symbol indicates the anticipated worth where-am-i. yet trying to unravel the logo utilizing get to the bottom of and utilizing syntax-quote returns what appears like (as revealed on the REPL) a namespace-qualified image. the reason is, a symbol’s qualification is a attribute of assessment and never inherent within the image in any respect. This additionally applies to symbols certified with classification names. This assessment habit will end up priceless after we speak about macros in bankruptcy eight, yet for now we will summarize the overarching thought often called Lisp-1 (Gabriel 2001). four. four. three Lisp-1 Clojure is what’s often called a Lisp-1, which purely potential it makes use of an identical identify answer for functionality and price bindings. In a Lisp-2 programming language like universal Lisp, those identify resolutions are played in a different way reckoning on the context of the emblem, be it in a functionality name place or a functionality argument place. there are lots of arguments for and opposed to either Lisp-1 and Lisp-2, yet opposed to Lisp-1 one draw back bears attention. as the related name-resolution scheme is used for services and their arguments, there’s a true threat of shadowing current features with different locals or Vars. identify shadowing isn’t unavoidably non-idiomatic if performed thoughtfully, but when performed by chance it could possibly bring about a few unforeseen and vague error. you'll want to take care while naming locals and defining new services in order that name-shadowing problems could be shunned. even though name-shadowing mistakes are usually infrequent, the convenience in a simplified mechanism for calling and passing firstclass services a ways outweighs the unfavorable. Clojure’s adoption of a Lisp-1 answer scheme makes for cleanser implementations and for this reason highlights the answer instead of muddying the waters with the nuances of symbolic search for. for instance, the easiest functionality highlights this completely within the approach that it takes the greater-than functionality > and calls it inside its physique as f: (defn most sensible [f xs] (reduce #(if (f % %2) % %2) xs)) (best > [1 three four 2 7 five 3]) ;=> 7 the same functionality physique utilizing a Lisp-2 language will require the intervention of one other functionality (in this example funcall) liable for invoking the functionality explicitly.