good to know: tcl static "regexp" is faster than tcl "string" operation

#!/usr/bin/env tclsh
proc test-1 { val } {
   if {[regexp ^:: $val]} {
     return true
   } else {
     return false
   }
}
proc test-2 { val } {
   if {[string range $val 0 1] eq "::"} {
     return true
   } else {
     return false
   }
}
set num 100000
puts 1=[time {test-1 ::otto} $num]
puts 2=[time {test-1 otto}   $num]
puts 3=[time {test-2 ::otto} $num]
puts 4=[time {test-2 otto}   $num]
 > ./sbin/time-check.tcl
1=1.26311 microseconds per iteration
2=1.09152 microseconds per iteration
3=1.44028 microseconds per iteration
4=1.43917 microseconds per iteration