is a global variable which, if set, is applied to any input string that is found to contain a syntax error.


  • The arguments given to $SyntaxHandler are the complete input string and an integer specifying the character position at which the syntax error was detected.
  • The first character in the string is taken to have position .
  • Any string returned by $SyntaxHandler is used as a new version of the input string, and is fed to Mathematica. If the string does not end with a newline, Mathematica waits for input to complete the line.
  • If $SyntaxHandler returns $Failed, input to Mathematica is abandoned if possible.
  • Input is not assigned to InString[n] until after $SyntaxHandler is applied.
  • $SyntaxHandler is not called for input from files obtained using Get.
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