replace.rap

proc REPLACE ( <=WHERE, =>WHAT, =>BY_WHAT )
    N:= 1
    do
        K:= index (WHAT, WHERE [N:])

        if K = 0 then
            exit
        fi
        K:= N+K-1
        WHERE[K:K+#WHAT-1]:= BY_WHAT

        N:= K + #BY_WHAT
    od
end

FAIRYTAIL:= "Somebody said," + lf + """Bother!""" + lf + "And then he said," + lf + """Oh, deary me!""" + lf + "Somebody sobbed, ""Oh, deary me!""" + lf + "And went back to bed."
REPLACE (<=FAIRYTAIL, =>"Somebody", =>"The King")
output: FAIRYTAIL