Of course there may be side effects. That is why you don't have to use -w. But there is no good reason to use grep and/or map solely for their side effects and there are good reasons to not do so. The warning would be: 

    Use of map/grep in void context, use foreach instead

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If you have some perverse reason for doing such, then just turn off that warning. For people wanting help in catching simple errors, the warning will be useful.

                - tye

In reply to Re^3: Operator precedence (void context) by tye
in thread Operator precedence (or, I'm an idiot) by Mur

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