Take the 2-minute tour ×
Mathematica Stack Exchange is a question and answer site for users of Mathematica. It's 100% free, no registration required.

Why does

Circle[{0, 0}] /. List[_?NumericQ ..] :> Sequence[]

return

Circle[{0, 0}]

yet

Circle[{0, 0}] /. List[_?NumericQ ..] :> List

returns

Circle[List]

?

share|improve this question

1 Answer 1

up vote 12 down vote accepted

This is because the definition of Circle[] is Circle[{0, 0}]. As soon as {0, 0} is replaced by Sequence[], this definition kicks in, thus rendering the replacement useless.

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.