Seems like there's some trickery involved with using Vars.
This example seems to use reflection.
user=> (.length ((fn ^String [^String s] (.substring s 0 (.length s))) "a"))
Reflection warning, NO_SOURCE_PATH:1:1 - reference to field length can't be
resolved.
1
Thanks,
Ambrose
On Tue, Jun 18, 2013 at 1:15 AM, Ambrose Bonnaire-Sergeant <
abonnaireserge...@gmail.com> wrote:
> Yes, it did. That's interesting. I have no idea where the .length method
> is being inferred from in the last example.
>
> Carry on :)
>
> Ambrose
>
>
> On Tue, Jun 18, 2013 at 1:10 AM, Jim - FooBar(); <jimpil1...@gmail.com>wrote:
>
>> so how about this then?
>>
>>
>> nREPL server started on port 43830
>> REPL-y 0.2.0
>> Clojure 1.5.1
>> Docs: (doc function-name-here)
>> (find-doc "part-of-name-here")
>> Source: (source function-name-here)
>> Javadoc: (javadoc java-object-or-class-here)
>> Exit: Control+D or (exit) or (quit)
>>
>> user=> (set! *warn-on-reflection* true)
>> true
>> user=> (defn foo [^String s] (.substring s 0 (.length s)))
>> #'user/foo
>> user=> (foo "jim")
>> "jim"
>> user=> (.length (foo "jim"))
>> *Reflection warning, NO_SOURCE_PATH:1:1 - reference to field length
>> can't be resolved.*
>> 3
>> user=> (defn foo ^String [^String s] (.substring s 0 (.length s)))
>> #'user/foo
>> user=> (.length (foo "jim"))
>> 3
>> user=> (defn ^String foo [^String s] (.substring s 0 (.length s)))
>> #'user/foo
>> user=> (.length (foo "jim"))
>> 3
>>
>>
>> it worked both times didn't it?
>>
>> Jim
>>
>>
>>
>>
>>
>> On 17/06/13 17:59, Ambrose Bonnaire-Sergeant wrote:
>>
>> After some investigation, the before-the-arglist syntax only seems useful
>> for defining fn's that return primitive types.
>> They don't seem to help resolve reflection calls.
>>
>> (require '[clojure.tools.analyzer :refer [ast]])
>>
>> ; this creates a double-emitting fn
>>
>> (ast (fn (^double [^double a] a)))
>> ; =>
>> ;{:op :fn-expr,
>> ; ...
>> ; :methods
>> ; ({:op :fn-method,
>> ; ...
>> ; :arg-types (#<Type Ljava/lang/Object;>),
>> ; :return-type #<Type D>}), ;double return type here
>> ; ...
>> ; :tag nil} ; no tag
>>
>> ; this creates a regular old fn
>>
>> (ast (fn (^String [a] 1)))
>> ; =>
>> ;{:op :fn-expr,
>> ; ...
>> ; ({:op :fn-method,
>> ; ...
>> ; :arg-types (#<Type Ljava/lang/Object;>),
>> ; :return-type #<Type Ljava/lang/Object;>}), ;object return type
>> ; ...
>> ; :tag nil} ; no tag
>>
>> ; this creates a String-hinted fn
>>
>> (ast ^String (fn a [a] 1))
>> ;{:op :meta,
>> ; ...
>> ; :expr
>> ; {:op :fn-expr,
>> ; ...
>> ; :methods
>> ; ({:op :fn-method,
>> ; :arg-types (#<Type Ljava/lang/Object;>),
>> ; :return-type #<Type Ljava/lang/Object;>}),
>> ; ...
>> ; :tag String}}
>>
>> I don't see where before-the-arglist is useful outside of primitive fns.
>>
>> Thanks,
>> Ambrose
>>
>> On Mon, Jun 17, 2013 at 7:59 PM, Jim - FooBar(); <jimpil1...@gmail.com>wrote:
>>
>>> Hi all,
>>>
>>> It seems to me that return type-hints can go either right after "defn",
>>> or after the doc-string. I generally, put the return type-hints right
>>> before the argument vector and it seems to get rid of reflection. However,
>>> I just had a look at core.contrib.strutils2 and the author(s) put the type
>>> hint right after 'defn' (before the var about to be defined) and again it
>>> gets rid of reflection! Which one is it? both are acceptable?
>>>
>>> thanks in advance,
>>>
>>> Jim
>>>
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