how to use sh:if

Dear all:

      I'm not very clear about the use of sh:if, The examples given in the SHACL-AF specification are relatively simple so I don't understand them very well.
Consider the following example:

if someone.height>180 then
       someone is tallPerson
else if someone.height>155 then
       someone is mediumPerson
else
       someone is shortPerson

How do I present it use sh:if in a shacl shape file?
Can the SHACL validation engine give an violation message for the following data files?
         :bob a :Person ;
                 :hasHeight 185 ;
                 a :shortPerson .
Because Bob, by definition, should be a tallPerson.

Thank you for your help!

Kind regards,
Joylix