flatten the instruction dispatch loop

src/lib/between.pl

@@ -12,9 +12,7 @@ between(Lower, Upper, X) :-
     (   nonvar(X) ->
         Lower =< X,
         X =< Upper
-    ;   % compare(Ord, Lower, Upper),
-        % between_(Ord, Lower, Upper, X)
-        Lower =< Upper,
+    ;   Lower =< Upper,
         between_(Lower, Upper, X)
     ).
 
@@ -27,16 +25,6 @@ between_(Lower, Upper, Lower1) :-
        )
     ).
 
-/*
-between_(<, Lower0, Upper, X) :-
-    (   X = Lower0
-    ;   Lower1 is Lower0 + 1,
-        compare(Ord, Lower1, Upper),
-        between_(Ord, Lower1, Upper, X)
-    ).
-between_(=, Upper, Upper, Upper).
-*/
-
 enumerate_nats(I, I).
 enumerate_nats(I0, N) :-
     I1 is I0 + 1,

src/lib/builtins.pl

@@ -59,15 +59,13 @@ call(G, A, B, C, D, E, F, G) :- '$call'(G, A, B, C, D, E, F, G).
 
 call(G, A, B, C, D, E, F, G, H) :- '$call'(G, A, B, C, D, E, F, G, H).
 
+% dynamic module resolution.
 
 Module : Predicate :-
     (  atom(Module) -> '$module_call'(Module, Predicate)
     ;  throw(error(type_error(atom, Module), (:)/2))
     ).
 
-
-% dynamic module resolution.
-
 :(Module, Predicate, A1) :-
     (  atom(Module) ->
        '$module_call'(A1, Module, Predicate)

src/lib/lists.pl

@@ -56,13 +56,16 @@ length(Xs, N) :-
     !,
     '$skip_max_list'(M, -1, Xs, Xs0),
     (  Xs0 == [] -> N = M
-    ;  var(Xs0)  -> length_addendum(Xs0, N, M)).
+    ;  var(Xs0)  -> length_addendum(Xs0, N, M)
+    ).
 length(Xs, N) :-
     integer(N),
-    N >= 0, !,
+    N >= 0,
+    !,
     '$skip_max_list'(M, N, Xs, Xs0),
     (  Xs0 == [] -> N = M
-    ;  var(Xs0)  -> R is N-M, length_rundown(Xs0, R)).
+    ;  var(Xs0)  -> R is N-M, length_rundown(Xs0, R)
+    ).
 length(_, N) :-
     integer(N), !,
     domain_error(not_less_than_zero, N, length/2).