Well your proc chrome() returns a string. In Nim returned values are not silently discarded by default, unless you apply discardable pragma to the proc.
So you can write in your code echo chrome() var myStr = chrome() discard chrome() Or, if you really intent to be able to discard the result, then see Nim manual for discardable pragma. Maybe chrome() proc is not really intended to return a result at all, so fix that proc.