[erlang-bugs] maps:map/2 incorrect transformation signature

Daniel Goertzen <>
Mon Oct 28 18:07:28 CET 2013

According to eep-43, the transformation function in maps:map/2 should
return a new value for each key and value provided.  However, the current
implementation expects the function to return a key/value tuple.

Eep-43 is consistent with dict:map/2, so I think the implementation should
be corrected (as opposed to the eep)

Failing example (expected result is #{abc => 124})

2> maps:map( fun(_K, V) -> V+1 end, #{abc => 123}).
** exception error: bad argument
     in function  maps:from_list/1
        called as maps:from_list("|")
     in call from maps:map/2 (maps.erl, line 195)

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