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(. receiver member args...) (. receiver (method args...))

Calls a member on receiver: with a method symbol, the instance call (. obj m args); with a class as receiver, the static (. Class m args). With no arguments -- (. System currentTimeMillis) -- it is the zero-argument static method when the host class has one, else the field read, like (Class/m). (. obj -field) and (. Class FIELD) read fields. An instance call whose receiver is a construction literal -- (.isEmpty (java.util.ArrayList.)) -- a let/if-let/when-let local bound to one, or a .. step's declared return -- (.. (java.util.ArrayList. [1]) (subList 0 1) (isEmpty)) -- and whose overloads at that arity all answer a primitive boolean, answers true/false like the oracle; so does one on a string, number or character when every overload at that arity of its class does. Any other host boolean keeps the shared java: unmarshal and prints nil for false. The receiver decides the path: a string takes the mapped core operation, which runs on every backend; anything else goes to java:call, which calls a string as a String, a number as its box and a character as a Character ((.codePointAt "abc" 0), (.compareTo 1 2)). Classes resolve dotted as written, through :import, or through java.lang. Runs on the interpreter and the JVM only -- the wasm backends reject java:.