It doesn't work, in your OP it incorrectly throws an exception when you
pass it nil.
:pre just takes a sequence of expressions which are executed like `do`, and
throws an exception if any expression returns a false value.
Thanks,
Ambrose
On Thu, Feb 13, 2014 at 7:53 PM, Mamun <mamuni...@gmail.com> wrote:
> HI Ambrose,
>
> Thanks for your reply. But why this one is working?
>
>
> (defn check-nil [v]
> {:pre [nil? v]}
> v)
>
> Br,
> Mamun
>
>
>
> On Thursday, February 13, 2014 11:51:31 AM UTC+1, Ambrose
> Bonnaire-Sergeant wrote:
>
>> Hi Mamun,
>>
>> This is the correct syntax (you're missing some parens).
>>
>> (defn check-keyword [v] {:pre [(keyword? v)]} v)
>>
>> Thanks,
>> Ambrose
>>
>>
>> On Thu, Feb 13, 2014 at 6:47 PM, Mamun <mamu...@gmail.com> wrote:
>>
>>> Hi
>>>
>>> I am just testing clojure :pre condition. But look like using keyword?,
>>> it is not working in clojure 1.5.1.
>>>
>>> (defn check-keyword [v] {:pre [keyword? v]} v)
>>>
>>> (defn check-nil [v] {:pre [nil? v]} v)
>>>
>>> (check-keyword "sdf") ;Not throwing exception here
>>>
>>> (check-nil nil) ;Throwing exception
>>>
>>>
>>>
>>> Br,
>>>
>>> Mamun
>>>
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