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

[tclsh] runs a REPL when ''not'' given a script to execute.

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 $res              ;# print
} ;# RS 2013-11-19
======
For debugger-like applications (like a breakpoint), I also include the command
======
    if {$line eq "c"} break
======
between the [gets] and the [catch], so the surrounding script can continue operation.

** See Also **

   * [commandloop]

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

   * [tclsh]

   * [tkcon]

   * [prompt]

<<categories>>Category Glossary