On Dec 13, 5:24 am, ajay gopalakrishnan <ajgop...@gmail.com> wrote:
> It tried the following in REPL and got no error. Personally, I feel that I
> should get an error because calling square on strings is wrong in both
> cases.
>
> Is there a way out of this in Clojure?
I hope you don't mind me bumping this old thread, but only yesterday I
stumbled upon the "assert-args" macro in the master branch's core.clj
that does something similar to what you want. Example usage:
(defmacro when-let
"bindings => binding-form test
When test is true, evaluates body with binding-form bound to the
value of test"
[bindings & body]
(assert-args when-let
(vector? bindings) "a vector for its binding"
(= 2 (count bindings)) "exactly 2 forms in binding vector")
... snip body ...
I haven't tested it, but it will probably be able throw a compile time
exception if used in a macro definition (with it's checking ability
being limited by what is known at compile/macro expansion time), and a
runtime exception if used in a function definition. So if you make use
of assert-args in the function that will later call square, the error
can at least be caught at runtime and generate a useful exception
message, regardless of whether (map square ...) will be evaluated or
not.
assert-args is a private var though, so a more officially idiomatic
way to check function arguments is probably to use the new pre/post
conditions slated for 1.1.
(Only when I had finished writing this post did I realize that you
really want static type inferrence, which assert-args doesn't provide,
but hopefully this information will be useful anyway :-)
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