I know you said clj-time solved this for you, but here's another way to
handle it which avoids using a macro (using a map of keywords to
java.util.Calendar weekday enums for convenience and to be more
Clojure-esque, but it isn't necessary):
user=> (def weekdays {:mon Calendar/MONDAY :tues Calendar/TUESDAY :wed
Calendar/WEDNESDAY :thurs Calendar/THURSDAY :fri Calendar/FRIDAY :sat
Calendar/SATURDAY :sun Calendar/SUNDAY})
#'user/weekdays
user=> (defn is-day-of-week? [day-enum] (= Calendar/DAY_OF_WEEK
(day-enum weekdays)))
#'user/is-day-of-week?
user=> (is-day-of-week? :sat)
false
user=> (is-day-of-week? :wed)
true
user=>
You don't need to use all the Java interop syntax you're using, you can
refer to and compare these static fields directly. In the end these are
simply Integer comparisons.
DD
(2013/08/14 11:45), Daniel Meneses Báez wrote:
> I don't know if you have a differente approach, but as a defn it doesn't
> work
>
> user> (import '[java.util Calendar])
> java.util.Calendar
> user> (defn is [s instant]
> (= (.get instant Calendar/DAY_OF_WEEK)
> (. Calendar s)))
> CompilerException java.lang.NoSuchFieldException: s,
> compiling:(NO_SOURCE_PATH:3:12)
>
> user> (defmacro is [s instant]
> `(= (.get ~instant Calendar/DAY_OF_WEEK)
> (. Calendar ~s)))
> #'user/is
> user> (is WEDNESDAY (Calendar/getInstance))
> true
>
> I think that when you declare this as a function it will it attempt to
> validate that Calendar has an 's' member, at this point that is an
> error, on the other hand when the macro gets replaced the generated form
> is valid.
>
> just for the fun of it, I got this working:
>
> user> (defmacro is [s]
> `#(= (.get % Calendar/DAY_OF_WEEK)
> (. Calendar ~s)))
> #'user/is
> user> ((is WEDNESDAY) (Calendar/getInstance))
> true
>
> now I can write what I had in mind
>
> user> (def is-friday (is FRIDAY))
> #'user/is-friday
> user> (is-friday (Calendar/getInstance))
> false
> user> (def is-wednesday (is WEDNESDAY))
> #'user/is-wednesday
> user> (is-wednesday (Calendar/getInstance))
> true
>
> cool xD
>
>
>
> On Wed, Aug 14, 2013 at 11:33 AM, Jim - FooBar(); <jimpil1...@gmail.com
> <mailto:jimpil1...@gmail.com>> wrote:
>
> why on earth is this a macro and not a regular fn?
>
>
> Jim
>
> On 14/08/13 16:19, Daniel Meneses wrote:
>> Hi!
>>
>> Thanks for your answer Sean I got it solved using clj-time
>>
>> Also I found the problem with my macro attempt
>>
>> user> (defmacro is
>> [s instant]
>> `(= (.get ~instant Calendar/DAY_OF_WEEK)
>> (. Calendar ~s)))
>> #'current-day.core/is
>> user> (is FRIDAY (Calendar/getInstance))
>> false
>> user> (is WEDNESDAY (Calendar/getInstance))
>> true
>>
>> I was quoting the symbol !!
>>
>> On Tuesday, August 13, 2013 8:21:39 PM UTC-4, Sean Corfield wrote:
>>
>> Perhaps clj-time might help you?
>>
>> https://github.com/clj-time/__clj-time
>> <https://github.com/clj-time/clj-time>
>>
>> (ns time.core
>> (:require [clj-time.core :as time]
>> [clj-time.local :as local]
>> [clj-time.predicates :as p]))
>>
>> (p/monday? (time/now)) ;; false
>> (p/tuesday? (time/now)) ;; false
>> (p/wednesday? (time/now)) ;; true (for me in California since
>> (time/now) is UTC)
>>
>> (p/monday? (local/local-now)) ;; false
>> (p/tuesday? (local/local-now)) ;; true (for me)
>> (p/wednesday? (local/local-now)) ;; false (not yet in California)
>>
>> Sean
>>
>> On Tue, Aug 13, 2013 at 3:14 PM, Daniel Meneses Báez
>> <dap...@gmail.com> wrote:
>> > Hi :)
>> >
>> > I really want to know if there is a way to do this:
>> >
>> > (ns ...
>> > (:import [java.util Calendar]))
>> >
>> > (defsomething ;; if it is possible using a macro I'm ok with
>> that
>> > calendar-member
>> > [member]
>> > (symbol (str "Calendar/" member)))
>> >
>> > what I want to know if an instance of Calendar "isMonday",
>> "isFriday"
>> > "isSunday" etc...
>> >
>> > so I was thinking to write something like
>> >
>> > (defn- isss [day instant]
>> > (= (.get instant Calendar/DATE) (calendar-member day)))
>> >
>> > and then use it like (def is-friday (partial isss 'FRIDAY)) ;;
>> >
>> > am I being to crazy?
>> >
>> > btw I'm really loving the language.
>> >
>> >
>> >
>> > --
>> > Daniel Meneses Báez
>> >
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>> An Architect's View -- http://corfield.org/
>> World Singles, LLC. -- http://worldsingles.com/
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