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Debugging in clojure
Jul. 21st, 2012 11:53 amFinding a bug in my code in 90% of the cases has two phases:
1. This part of the code I wrote is correct, this must be compiler/library bug!
2. I think "ohh, how stupid was I writing that in the first place. This is so trivial and is of course a my fault!"
From the session above, looks like something really wrong is happening with clojure, it can't be that calling a pure function from map is different from calling it with explicit arguments. However I am 90% sure that after I debug the buggy-fn, I will find my coding error.
Upd: Found it, the function buggy-fn is not pure, so it was a side effect.
1. This part of the code I wrote is correct, this must be compiler/library bug!
2. I think "ohh, how stupid was I writing that in the first place. This is so trivial and is of course a my fault!"
=> (map buggy-fn array) < classcastexception java.lang.Long cannot be cast to clojure.lang.IFn > => (count array) 2 => (buggy-fn (first array)) () => (buggy-fn (second array)) () ; Let's try contrib.trace! Never done that... => (defn reproduce [array] (map buggy-fn array)) => (dotrace [reproduce] (reproduce)) # < illegalstateexception dynamically="dynamically" bind="bind" non-dynamic="non-dynamic" var:="var:" > ; Ooops - does not work, will have to resort to debug/dbg output traces as usual.
From the session above, looks like something really wrong is happening with clojure, it can't be that calling a pure function from map is different from calling it with explicit arguments. However I am 90% sure that after I debug the buggy-fn, I will find my coding error.
Upd: Found it, the function buggy-fn is not pure, so it was a side effect.
