'''REPL''', or '''Read-Evaluate-Print Loop''' is the basic mode of operation of
a [shell].

Simple example in Tcl:
 set prompt "% "
 while 1 {
    puts -nonewline $prompt
    flush stdout
    gets stdin line        ;# read...
    if [eof stdin] break
    catch $line res        ;# eval...
    puts $res              ;# print
 }


** See Also **

   [commandloop]:   

   [An interactive tclsh with an event loop (but no Tk)]:   

   [tclsh]:   

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