I just added a new library to clojure.contrib: clojure.contrib.macro- utils. It provides three macros that are useful in writing other macros:
- macrolet (syntax like letfn) provides local macros that are active only inside the body of the macrolet form. - symbol-macrolet provides local symbol macros. - defsymbolmacro defines global symbol macros. Symbol macros are textual replacements for symbols; they have no parameters. Wherever a symbol defined as a macro occurs in a form, it is replaced by the symbol macro's value, EXCEPT where the symbol names a function argument or receives a binding in a let form. The replacement value is again subjected to macro expansion, until the result no longer changes. This is the same behaviour as for standard macros. While macrolet and symbol-macrolet just work as expected, global symbol macros require the use of the (with-symbol-macros ...) form around the expression(s) where they are used. This is because Clojure's macro system doesn't know anything about symbol macros otherwise. (with-symbol-macros ...) uses a complete re-implementation of macro expansion that knows about symbol and local macros. The same implementation is used by macrolet and symbol-macrolet. The expressions inside these forms are handed back to Clojure's compiler already fully expanded. Macrolet and symbol-macrolet are most useful in defining other macros. Typically, a macro would expand into a form containing macrolet and/or symbol-macrolet for defining values or operations for use inside the body of the expansion. The library also provides three functions for testing and debugging macro expansions: - mexpand-1 works like macroexpand-1 but knows about symbol macros - mexpand works like macroexpand but knows about symbol macros - mexpand-all does a full recursive macro expansion Any feedback is welcome. Konrad. --~--~---------~--~----~------------~-------~--~----~ 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 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 -~----------~----~----~----~------~----~------~--~---
