/*  Pretty-printing.  Print only if (printctl on)  */

( (printif List)
    (printctl on)
    (cut)
    (printall List)
)
( (printif _) )

( (displayif Thing)
    (printctl on)
    (cut)
    (display Thing)
)
( (displayif _) )

( (pctl on)
    (cut)
    (asserta (printctl on))
)
( (pctl off)
    (retract (printctl _))
)

( (pstdout on)
    (cut)
    (asserta (printstdout on))
)
( (pstdout off)
    (retract (printstdout _))
)

( (statctl on)
    (cut)
    (asserta (statctl on))
)
( (statctl off)
    (retract (statctl _))
)

( (tostring nl "")
    (cut)
    (tracenl)
    /* (nl) */
)

( (tostring X X)
    (string X)
    (cut)
)
( (tostring X Y)
    (atom X)
    (cut)
    (string_from X Y)
)
( (tostring X Y)
    (integer X)
    (cut)
    (string_from X Y)
)
( (tostring X "<_var_>")
    (var X)
)
(printall ())

( (printall (H|T))
    (tostring H Sh)
    (tracewrites Sh)
    /* (writes Sh) */
    (printall T)
)