No, you shouldn't worry about that) In fact it was useful to me to learn
that Clojure does not support array type hints everywhere. It may be
possible that I will have to change some of my code because of this.
вторник, 18 декабря 2012 г., 23:30:39 UTC+4 пользователь David Nolen
написал:
>
> Ah right, sorry to mislead.
>
>
> On Tue, Dec 18, 2012 at 2:26 PM, Vladimir Matveev
> <dpx.in...@gmail.com<javascript:>
> > wrote:
>
>> Thanks, but it seems that I have found the source of problem, though I do
>> not know why compiler message is so uninformative and misleading.
>>
>> The following code does not work (fails with CompilerException
>> java.lang.VerifyError: (class: test/Test2Impl, method: fail signature: ()V)
>> Expecting to find integer on stack):
>>
>> (definterface Test2
>> (^void fail []))
>>
>> (deftype Test2Impl
>> [^{:unsynchronized-mutable true :tag int} x]
>> Test2
>> (fail [this]
>> (set! x (dec x))))
>>
>> The following code _does_ work:
>>
>> (definterface Test2
>> (^void fail []))
>>
>> (deftype Test2Impl
>> [^{:unsynchronized-mutable true :tag int} x]
>> Test2
>> (fail [this]
>> (set! x (int (dec x)))))
>>
>> Note that I have wrapped (dec x) into (int). This compiles and works
>> flawlessy.
>>
>> In fact it is fine that there is an error here because (dec) is defined
>> only on objects and longs, so supplying int to it does not work as
>> intended. Even my first example in this message will work if you replace
>> :tag int with :tag long.
>> However, error message is absolutely misleading and seems to be a
>> consequence of an error in the compiler...
>>
>>
>>
>> вторник, 18 декабря 2012 г., 23:18:28 UTC+4 пользователь David Nolen
>> написал:
>>>
>>> Oops, looking over gvec.clj it looks like I'm wrong about type-hinting
>>> fields. However you may need to type-hint the primitive array with a string
>>> instead of the symbol shorthand allowed by Clojure. Try the following:
>>>
>>> ^{:tag "[I" :unsynchronized-mutable true}
>>>
>>> David
>>>
>>>
>>> On Tue, Dec 18, 2012 at 1:46 PM, Vladimir Matveev
>>> <dpx.in...@gmail.com>wrote:
>>>
>>>> Well, it is news for me since it is not documented anywhere. Why is
>>>> this so? BTW, typehinting value in '(let [value (aget data depth)]'
>>>> binding
>>>> gives an error "Can't type hint a local with a primitive initializer" so I
>>>> think since this value considered primitive then I actually can hint the
>>>> fields to be primitive arrays.
>>>> Nonetheless, it does not look like that problem is in the field array:
>>>> wrapping aget form with (int) does not help.
>>>>
>>>> вторник, 18 декабря 2012 г., 17:46:14 UTC+4 пользователь David Nolen
>>>> написал:
>>>>
>>>>> I don't think you can type hint a field as a primitive array.
>>>>>
>>>>> On Tuesday, December 18, 2012, Vladimir Matveev wrote:
>>>>>
>>>>>> Hello,
>>>>>>
>>>>>> Consider the following code
>>>>>>
>>>>>> (gen-interface
>>>>>> :name IntStack
>>>>>> :methods [[stackPeek [] int]
>>>>>> [stackPush [int] void]
>>>>>> [stackPop [] int]
>>>>>> [stackDepth [] int]])
>>>>>>
>>>>>> (deftype IntStackImpl
>>>>>> [^{:tag ints :unsynchronized-mutable true} data
>>>>>> ^{:tag int :unsynchronized-mutable true} depth]
>>>>>> IntStack
>>>>>> (stackPeek [this]
>>>>>> (aget data depth))
>>>>>> (stackPush [this value]
>>>>>> (when (>= (inc depth) (alength data))
>>>>>> (let [data-length (alength data)
>>>>>> new-data (int-array (* data-length 2))]
>>>>>> (System/arraycopy data 0 new-data 0 data-length)
>>>>>> (set! data new-data)))
>>>>>> (set! depth (inc depth))
>>>>>> (aset data depth value))
>>>>>> (stackPop [this]
>>>>>> (if (> depth 0)
>>>>>> (let [value (aget data depth)]
>>>>>> (set! depth (dec depth))
>>>>>> value)
>>>>>> (throw (IllegalStateException. "Stack is already empty!"))))
>>>>>> (stackDepth [this]
>>>>>> depth))
>>>>>>
>>>>>> This is very simple stack implementation over plain java array. It
>>>>>> does not compile with the following message:
>>>>>> CompilerException java.lang.VerifyError: (class:
>>>>>> clojure/data/xml/IntStackImpl, method: stackPop signature: ()I)
>>>>>> Expecting
>>>>>> to find integer on stack
>>>>>>
>>>>>> However, when I replace the body of stackPop with, say, plain zero
>>>>>> literal 0, the method seems to pass the compilation, because then I'm
>>>>>> getting similar error on stackPush method instead.
>>>>>> Placing type hints inside stackPop method does not work (in fact, it
>>>>>> is even an error to place them, say, on value local binding).
>>>>>>
>>>>>> What am I doing wrong here? How to make the class compile?
>>>>>>
>>>>>> Cheers,
>>>>>> Vladimir.
>>>>>>
>>>>>>
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