File psl-1983/tests/mini-easy-sl.red artifact 5c170ce9c8 part of check-in 955d0a90a7

% MINI-EASY-SL.RED --- Simple functions


% --- Some basic predicates
% Note that the bodies open copile, so this is just for
% interpreter entries

Procedure Atom x;
 Atom x;

% Simple LIST stuff

Procedure append(U,V);
 if not PairP U then V
  else Cons(Car U,Append(Cdr U,V));

Procedure MemQ(x,y);
 If Not PAIRP y then NIL
  else if x EQ car y then T
  else MemQ(x, cdr y);

Procedure REVERSE U;
 Begin Scalar V;
   While PairP U do <<V:=CONS(Car U,V); 
                      U:=CDR U>>;
   Return V;
 End;

% Simple EVAL support

procedure Evlis x;
 if Not Pairp x then x
  else Eval(car x) . Evlis(cdr x);

procedure EvProgn fl;
  Begin scalar x;
    While PairP fl do <<x:=Eval Car fl;
                        fl:=Cdr fl>>;
    Return x;
  End;

fexpr procedure Progn x;
  EvProgn x;

procedure EvCond fl;
  if not PairP fl then 'NIL
   else if not PairP car fl then EvCond cdr fl
   else if Eval car car fl then EvProgn cdr car fl
   else EvCond cdr fl;

fexpr procedure Cond x;
  EvCond x;

Fexpr Procedure Quote a;
 Car a;

Fexpr Procedure SETQ a;
 Set(car a,Eval Cadr a);

fexpr Procedure De(x);
  PutD(car x,'Expr,'LAMBDA . cdr x);

fexpr Procedure Df(x);
  PutD(car x,'Fexpr,'LAMBDA . Cdr x);

fexpr Procedure Dn(x);
  PutD(car x,'NExpr,'LAMBDA . cdr x);

fexpr Procedure Dm(x);
  PutD(car x,'Macro,'LAMBDA . Cdr x);


nexpr procedure List x;
 x;


End;