10 votes
Accepted

RuleDelayed (:>) involving Piecewise leads to Piecewise::pairs warning in ReplaceAll (/.)

While creating the delayed rule Mathematica evaluates the left hand side of the rule by default. Evaluating Piecewise[a_, b___] returns the error message, but stays ...
  • 18.3k
7 votes
Accepted

Ask Mathematica to always print errors in InputForm

Use $MessagePrePrint. $MessagePrePrint = InputForm;
  • 11.6k

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