More exception stuff

src/base.h

@@ -353,6 +353,8 @@ DECLARE_FUNCTION(setplist, (LispVal * sym, LispVal *plist));
 DECLARE_FUNCTION(get, (LispVal * sym, LispVal *key, LispVal *def));
 DECLARE_FUNCTION(put, (LispVal * sym, LispVal *key, LispVal *val));
 
+noreturn void signal_value_constant(LispVal *value);
+
 static ALWAYS_INLINE LispVal *SYMBOL_VALUE(LispVal *sym) {
     assert(SYMBOLP(sym));
     LispSymbol *s = (LispSymbol *) sym;
@@ -379,12 +381,11 @@ static ALWAYS_INLINE bool DYNAMIC_SYMBOL_P(LispVal *sym) {
     return ((LispSymbol *) sym)->flags & SYMBOL_DYNAMIC;
 }
 
-static ALWAYS_INLINE void SET_SYMBOL_VALUE(LispVal *sym, LispVal *value) {
+static inline void SET_SYMBOL_VALUE(LispVal *sym, LispVal *value) {
     assert(SYMBOLP(sym));
     LispSymbol *s = (LispSymbol *) sym;
     if (CONST_VALUE_P(sym)) {
-        // TODO throw
-        abort();
+        signal_value_constant(sym);
     }
     switch (s->value_type) {
     case SYMBOL_NORMAL:
@@ -425,6 +426,9 @@ MAKE_CONDITION_CLASS(error);
 DECLARE_SYMBOL(type_error);
 MAKE_CONDITION_CLASS(type_error);
 
+DECLARE_SYMBOL(value_constant_error);
+MAKE_CONDITION_CLASS(value_constant_error);
+
 // Defined in lisp code (eventually) but used in read.c
 DECLARE_SYMBOL(backquote);
 DECLARE_SYMBOL(comma);