|Odd name-sensitive behaviour||Chris Spencer||3/20/13 3:07 AM|
Was just trying out some basic protocol/datatype types and found an odd case where the naming of the protocol changes whether an exception is thrown or not.
(:require [clojure.core.typed :as t]))
adder [AddProtoc Number -> AddProtoc])
(adder [this amount]))
(t/ann-datatype Accumulator [t :- Number])
(deftype Accumulator [t]
(adder [_ i] (Accumulator. (+ t i))))
(t/ann t [Number -> Accumulator])
(defn t [i] (Accumulator. i))
(t/ann t2 [Number -> AddProtoc])
(defn t2 [i] (Accumulator. i))
"Checking line:" 4
"Checking line:" 7
"Checking line:" 10
"Checking line:" 12
"Checking line:" 16
"Checking line:" 17
"Checking line:" 19
"Checking line:" 20
IllegalArgumentException Multiple methods in multimethod 'subtype*' match dispatch value: [clojure.core.typed.Protocol clojure.core.typed.Protocol :clojure.core.typed/clojure] -> [clojure.core.typed.Protocol :clojure.core.typed/Type :clojure.core.typed/clojure] and [clojure.core.typed.Protocol clojure.core.typed.Protocol :clojure.core.typed/default], and neither is preferred clojure.lang.MultiFn.findAndCacheBestMethod (MultiFn.java:136)
Doesn't occur if name of protocol changed to AddProto. The same exception is thrown when named AddProto but with an incompatible type given for the adder in the protocol (such as [AddProto Number -> Number]). Both are thrown on line 20 (the checking of t2)
This is with clojure 1.4 on windows.
|Re: Odd name-sensitive behaviour||Chris Spencer||3/20/13 3:15 AM|
Of course, I realise the actual issue just after posting: can't just reload the namespace in repl. So that's a bit more understandable.
However, setting the protocol definition to:
adder [AddProtoc Number -> Number])
With the above code now checks fine, even though adder returns an Accumulator in its definition.
|Odd name-sensitive behaviour||Ambrose Bonnaire-Sergeant||3/20/13 7:56 AM|
(Accidentally didn't to send this to the list)
On Wed, Mar 20, 2013 at 9:00 PM, Chris Spencer <chris.ag...@gmail.com> wrote:
Thanks, that really helps narrow the problem. I've created an issue: http://dev.clojure.org/jira/browse/CTYP-21
The way it currently works is meant to help with REPL driven development. Just re-evaluating an ann-protocol should update its type. The unsurprisingly comes with all the pitfalls of (a persistent) REPL.
|Re: Odd name-sensitive behaviour||Ambrose Bonnaire-Sergeant||3/20/13 7:20 PM|
|Re: Odd name-sensitive behaviour||Ambrose Bonnaire-Sergeant||3/20/13 9:47 PM|
Doh, I probably can't reproduce because I just fixed it yesterday :)
I've resolved the issue on Jira.