read from streams.

src/prolog/toplevel.pl

@@ -0,0 +1,19 @@
+repl :-
+    catch(read_and_match, E, '$print_exception'(E)),
+    false. %% this is for GC, until we get actual GC.
+repl :- repl.
+    
+read_and_match :-
+    read_term(Term, [variable_names(VarList)]),
+    '$instruction_match'(Term, VarList).
+
+'$instruction_match'([user], []) :-
+    !, '$compile_batch'.
+'$instruction_match'(Term, VarList) :-
+    '$submit_query_and_print_results'(Term, VarList),
+    !.
+
+'$print_exception'(E) :-
+    write_term('error: exception thrown: ', [quoted(false)]),
+    writeq(E),
+    nl.