id = 177
group = 'denotational_semantics'
number = 84
visible = True
facts = None

solution = '''\
algol_if(fun(S0,S,apply177([printout=[]|S0],S,Minstructs))) -->
  [begin], instructs177(Minstructs), [end].

instructs177(Minstr) --> instr177(Minstr).
instructs177(fun(S0,S,
  (apply177(S0,S1,Minstr),
   apply177(S1,S,Minstructs)))) 
  --> 
  instr177(Minstr), instructs177(Minstructs).

instr177(Massign) --> assign177(Massign).
instr177(fun(S0,[printout = L1|S1],
  (memb(X = V,S0),
   del(printout = L0,S0,S1),
   conc(L0,[V],L1))))
  -->
  [print(X)].
instr177(fun(S0,S,
  loop177(S0,Mcond,Minstructs,S)))
  -->
  [while], cond177(Mcond), [do,begin], instructs177(Minstructs), [end].
instr177(fun(S0, S,
  (apply177(S0, true, Mcond), !,
   apply177(S0, S, MinstructsA)
   ;
   apply177(S0, S, MinstructsB))))
  -->
  [if], cond177(Mcond), [then], instructs177(MinstructsA), [else], instructs177(MinstructsB), [end].

assign177(fun(S0,[X = Value|S1], 
  (apply177(S0,Value,Mexpr),
   del(X = _,S0,S1)))) 
  -->
  var177(X), [:=], expr177(Mexpr).

cond177( fun( S, TruthVal,
  (apply177(S,Val1,ME1),
   apply177(S,Val2,ME2),
   (Val1 < Val2,!,TruthVal = true ; TruthVal = false))))
  -->
  expr177(ME1), [<], expr177(ME2).

var177(X) --> [X], {atom(X)}.

expr177(fun(S,Value,eval(Expr,S,Value))) -->
  [Expr].

apply177(In, Out, fun(In, Out, Goals)) :-
  call(Goals).

loop177( State0, Mcond, _, State0) :-
  apply177( State0, false, Mcond), !.
loop177( S0, Mcond, MBody, S) :- 
  copy_term( MBody, MBodyCopy),
  apply177( S0, S1, MBody),
  loop177( S1, Mcond, MBodyCopy, S).

eval177( N, _, N) :-
  number177( N), !.
eval177( X, State, Val) :- % A program variable
  atom( X), !, 
  memb( X = Val, State). 
eval177( E1 + E2, State, Val) :- !,
  eval177( E1, State, V1),
  eval177( E2, State, V2),
  Val is V1 + V2.
eval177( E1 - E2, State, Val) :- !,
  eval177( E1, State, V1),
  eval177( E2, State, V2),
  Val is V1 - V2.
eval177( E1 * E2, State, Val) :- !,
  eval177( E1, State, V1),
  eval177( E2, State, V2),
  Val is V1 * V2.
eval177( E1 / E2, State, Val) :- !,
  eval177( E1, State, V1),
  eval177( E2, State, V2),
  Val is V1 /  V2.
'''