[discuss what tcl considers a variable of type *wide*]

An expr function that converts a number to a "wide integer" (i.e. an integer of at least 64-bits precision).

**expr**{**wide**(*value*) }

As JH observes on comp.lang.tcl, if you want a wide result, be sure to apply wide to one of the values in the expression - not the result of the expression.

In other words, this will not give you a wide result:

expr {wide( 80 * 1000000000 )}

while this will:

expr {wide( 80 ) * 1000000000 }

Of course, this applies to Tcl 8.4 and earlier. With Tcl 8.5, the expression works without the **wide** as *all* integers are considered to be of logically infinite width (and occupy as much space at the implementation level as needed to achieve this).