int eval(int addr){
int res;
if(atomp(addr)){
if(IS_NUMBER(addr))
return(addr);
if(IS_SYMBOL(addr)){
res = findsym(GET_NAME(addr));
switch(GET_TAG(res)){
case NUM: return(makenum(GET_NUMBER(res)));
case SYM: return(GET_BIND(res));
case LIS: return(GET_BIND(res));
}
}
}
else{
if(HAS_NAME(car(addr),"quote"))
return(cadr(addr));
if(subrp(car(addr)))
return(apply(symname(car(addr)),evlis(cdr(addr))));
if(fsubrp(car(addr)))
return(apply(symname(car(addr)),cdr(addr)));
if(lambdap(car(addr)))
return(apply(symname(car(addr)),evlis(cdr(addr))));
}
return(NIL);
}
int read(void){
gettoken();
switch(stok.type){
case NUMBER: return(makenum(atoi(stok.buf)));
case SYMBOL: return(makesym(stok.buf));
case QUOTE: return(cons(makesym("quote"), cons(read(),makeempty())));
case LPAREN: return(readlist());
}
}
int read(void){
gettoken();
switch(stok.type){
case NUMBER: return(makenum(atoi(stok.buf)));
case SYMBOL: return(makesym(stok.buf));
case QUOTE: return(cons(makesym("quote"), cons(read(),makeNIL())));
case LPAREN: return(readlist());
}
error(CANT_READ_ERR,"read",NIL);
}
int f_minus(int arglist){
int arg,res;
res = GET_NUMBER(car(arglist));
while(!(IS_NIL(arglist))){
arg = GET_NUMBER(car(arglist));
arglist = cdr(arglist);
res = res - arg;
}
return(makenum(res));
}
int f_plus(int arglist){
int arg,res;
checkarg(NUMLIST_TEST, "+", arglist);
res = 0;
while(!(IS_NIL(arglist))){
arg = GET_NUMBER(car(arglist));
arglist = cdr(arglist);
res = res + arg;
}
return(makenum(res));
}
int f_length(int arglist){
checkarg(LEN1_TEST, "length", arglist);
checkarg(LIST_TEST, "length", car(arglist));
return(makenum(length(car(arglist))));
}