Ninth bullet point in Paul Graham's What Made Lisp Different says,
9. The whole language always available.
There is no real distinction between read-time, compile-time, and runtime. You can compile or run code while reading, read or run code while compiling, and read or co开发者_开发技巧mpile code at runtime.
Running code at read-time lets users reprogram Lisp's syntax; running code at compile-time is the basis of macros; compiling at runtime is the basis of Lisp's use as an extension language in programs like Emacs; and reading at runtime enables programs to communicate using s-expressions, an idea recently reinvented as XML.
Does this last bullet point hold for Clojure?
You can mix runtime and compile-time freely in Clojure, although Common Lisp is still somewhat more flexible here (due to the presence of compiler macros and symbol macros and a fully supported macrolet
; Clojure has an advantage in its cool approach to macro hygiene through automagic symbol resolution in syntax-quote). The reader is currently closed, so the free mixing of runtime, compile-time and read-time is not possible1.
1 Except through unsupported clever hacks.
It does hold,
(eval (read-string "(println \"Hello World!!\")"))
Hello World!!
nil
Just like emacs you can have your program configuration in Clojure, one project that I know Clojure for is static which allows you to have your template as a Clojure vector along with arbitrary code which will be executed at read time.
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