Hi Rich,
for your first issue "declare" does exactly what you want.
=> (doc declare)
-------------------------
clojure.core/declare
([& names])
Macro
defs the supplied var names with no bindings, useful for making
forward declarations.
nil
Cheers,
Paul.
2009/3/10 Rich <rwml...@gmail.com>:
>
> I'm relatively new to Clojure, and I just want to make sure I
> understand things correctly. There are two issues that I'm struggling
> with. Neither is major, but if there is a good solution, I'd like to
> find out.
>
> 1) You must define a method before you call it from another function.
> Stylistically, I prefer to define helper functions after the main
> function, but that seems to cause errors. If I move them in front of
> the main function, the errors go away. I don't know if there's some
> way to declare the methods before you define them (like C header
> files).
>
> 2) To have two or more functions with the same name and a different
> arity, you must define them in a single (defn...).
>
> For example, the following code:
>
> (defn good
> ([a] (println (str "argument: " a)))
> ([a, b] (println (str "arguments: " a ", " b))))
>
> (defn bad [a] (str "argument: " a))
> (defn bad [a b] (str "arguments:" a ", " b))
>
>
> (good "foo")
> (good "foo" "bar")
> (bad "foo")
> (bad "foo" "bar")
>
> Generates the following output:
>
> argument: foo
> arguments: foo, bar
> Exception in thread "main" java.lang.IllegalArgumentException: Wrong
> number of args passed to: core$bad (SandBox.clj:0)
>
> This crops up when I have a function that was created using a function-
> building macro, and I wanted to define a wrapper with the same name
> that allowed me to enter the arguments in a simpler manner.
>
> Also, it just feels odd. You don't get an error when defining the same-
> named function--but suddenly neither version works. That's a pretty
> serious side-effect. So maybe this is just a bug?
>
> Thanks,
>
> -Rich-
>
>
> >
>
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