Andy Wardley writes: 
> Because Perl is a general purpose programming language. 
> TT implements 
> a general purpose presentation language.  A different 
> kettle of fish altogether. 
 
These are the reserve words of TT: 
 
    GET CALL SET DEFAULT INSERT INCLUDE PROCESS WRAPPER  
    IF UNLESS ELSE ELSIF FOR FOREACH WHILE SWITCH CASE 
    USE PLUGIN FILTER MACRO PERL RAWPERL BLOCK META 
    TRY THROW CATCH FINAL NEXT LAST BREAK RETURN STOP  
    CLEAR TO STEP AND OR NOT MOD DIV END 
 
Looks an awful lot like the same keywords in any general-purpose 
programming language.