Change to date format as part of statement

[SI_NY02]

I have the following if statement, which returns the correct answer, but I need it to be in date format "MMM-DD-YYYY".  How do I add that? 

=if(DateType = 'Open Date', CanonicalDate,'')

[BrunPierre · Accepted solution]

This?

=If(DateType = 'Open Date', Date(CanonicalDate, 'MMM-DD-YYYY'), Null())