Tcl 8 brought “dual-ported values” (among other things) to the table. Values were stored in “objects” (not to be confused with object-oriented programming objects) whereby the “string representation” was always available (“everything is a string” (eias) is a core logical tenet of Tcl, and has not gone away), and a “native representation” is available for (context-dependant) performance reasons. What does this mean? If you have “set a 0.8657309”, and do math ops with it, backing object will have a native float type available to do its work by. Previous to Tcl 8, the logical language promise of eias held, but the implementation within the Tcl interp was a char* array of bytes, too. That was a long time ago, though.