id = 178
group = 'denotational_semantics'
number = 85
visible = True
facts = None

solution = '''\
algol_for(fun(S0,S,apply178([printout=[]|S0],S,Minstructs))) -->
  [begin], instructs178(Minstructs), [end].

instructs178(Minstr) --> instr178(Minstr).
instructs178(fun(S0,S,
  (apply178(S0,S1,Minstr),
   apply178(S1,S,Minstructs)))) 
  --> 
  instr178(Minstr), instructs178(Minstructs).

instr178(Massign) --> assign178(Massign).
instr178(fun(S0,[printout = L1|S1],
  (memb(X = V,S0),
   del(printout = L0,S0,S1),
   conc(L0,[V],L1))))
  -->
  [print(X)].
instr178(fun(S0,S,
  loop178(S0,Mcond,Minstructs,S)))
  -->
  [while], cond178(Mcond), [do,begin], instructs178(Minstructs), [end].
instr178(fun(S0, S,
  (apply178(S0, S1, Minit),
   for178(S1, Mcond, Mstep, Mbody, S))))
  -->
  [for], assign178(Minit), [&], cond178(Mcond), [&], assign178(Mstep), [do, begin], instructs178(Mbody), [end].

assign178(fun(S0,[X = Value|S1], 
  (apply178(S0,Value,Mexpr),
   del(X = _,S0,S1)))) 
  -->
  var178(X), [:=], expr178(Mexpr).

cond178( fun( S, TruthVal,
  (apply178(S,Val1,ME1),
   apply178(S,Val2,ME2),
   (Val1 < Val2,!,TruthVal = true ; TruthVal = false))))
  -->
  expr178(ME1), [<], expr178(ME2).

var178(X) --> [X], {atom(X)}.

expr178(fun(S,Value,eval(Expr,S,Value))) -->
  [Expr].

apply178(In, Out, fun(In, Out, Goals)) :-
  call(Goals).

loop178( State0, Mcond, _, State0) :-
  apply178( State0, false, Mcond), !.
loop178( S0, Mcond, MBody, S) :- 
  copy_term( MBody, MBodyCopy),
  apply178( S0, S1, MBody),
  loop178( S1, Mcond, MBodyCopy, S).

for178(S0, Mcond, _, _, S0) :-
  apply178(S0, false, Mcond), !.
for178(S0, Mcond, Mstep, Mbody, S) :-
  copy_term(Mbody, Mbody2),
  copy_term(Mstep, Mstep2),
  apply178(S0, S1, Mbody),
  apply178(S1, S2, Mstep),
  for178(S2, Mcond, Mstep2, Mbody2, S).

eval178( N, _, N) :-
  number178( N), !.
eval178( X, State, Val) :- % A program variable
  atom( X), !, 
  memb( X = Val, State). 
eval178( E1 + E2, State, Val) :- !,
  eval178( E1, State, V1),
  eval178( E2, State, V2),
  Val is V1 + V2.
eval178( E1 - E2, State, Val) :- !,
  eval178( E1, State, V1),
  eval178( E2, State, V2),
  Val is V1 - V2.
eval178( E1 * E2, State, Val) :- !,
  eval178( E1, State, V1),
  eval178( E2, State, V2),
  Val is V1 * V2.
eval178( E1 / E2, State, Val) :- !,
  eval178( E1, State, V1),
  eval178( E2, State, V2),
  Val is V1 /  V2.
'''