[CLJ-848] defn :or form does not warn you if you provide a vector instead of a map

Tue, 25 Oct 2011 18:04:23 -0500

I had a problem defining a function today, I passed :or a vector instead of a map - everything seemed to work fine but later on I got a really puzzling "Null pointer exception".

raek helped me debug the problem and suggested opening this ticket. I think it would be useful if an exception was thrown on the :or line unless it's given a map.

Here are some examples

(defn broken-example [{:keys [i processor]
:or [processor identity]}]
(processor i))

(defn working-example [{:keys [i processor]
:or {processor identity}}]
(processor i))

(working-example {:i 1})
=> 1
(broken-example {:i 1})
=> Null pointer exception

Cheers, Dave.

Clojure JIRA

[CLJ-848] defn :or form does not warn you if you provide a vector instead of a map