From e195d66a333102924bae452ba09dc20cba4e96e6 Mon Sep 17 00:00:00 2001
From: Peter Mikkelsen <peter@pmikkelsen.com>
Date: Wed, 9 Feb 2022 13:08:12 +0000
Subject: Since symbols now have pointers to their values, we don't need the
 symbol.undefined field anymore

---
 apl9.h      | 1 -
 eval.c      | 7 ++-----
 quadnames.c | 1 -
 symbol.c    | 9 ++-------
 4 files changed, 4 insertions(+), 14 deletions(-)

diff --git a/apl9.h b/apl9.h
index 8b32141..3f592d9 100644
--- a/apl9.h
+++ b/apl9.h
@@ -158,7 +158,6 @@ struct Datum
 
 struct Symbol
 {
-	int undefined;
 	Rune *name;
 	Datum *value;
 	Datum *(*getfn)(void);
diff --git a/eval.c b/eval.c
index b7515b1..ea7e84f 100644
--- a/eval.c
+++ b/eval.c
@@ -141,7 +141,7 @@ lookup(Datum *var)
 	traceprint("VAR LOOKUP %S\n", var->name);
 	Symbol *symbol = getsym(var->name, 0);
 
-	if(symbol->undefined){
+	if(symbol->value == nil && symbol->getfn == nil){
 		Rune *msg = runesmprint("Undefined name: %S", var->name);
 		throwerror(msg, EValue);
 	}
@@ -259,12 +259,9 @@ assign(Datum *left, Datum *right)
 		else{
 			/* re-assign the symbol to one that is sure to be local. This enables shadowing */
 			symbol = getsym(symbol->name, 1);
-
-			if(symbol->undefined == 0)
-				freedatum(symbol->value);
+			freedatum(symbol->value);
 			symbol->value = right;
 			incdatumref(right);
-			symbol->undefined = 0;
 			if(symbol->value->tag == ArrayTag)
 				symbol->value->array->stranded = 0;
 		}
diff --git a/quadnames.c b/quadnames.c
index 57c5dbb..209c339 100644
--- a/quadnames.c
+++ b/quadnames.c
@@ -61,7 +61,6 @@ initquadnames(void)
 			s = getsym(q.name, 1);
 			s->getfn = q.get;
 			s->setfn = q.set;
-			s->undefined = 0;
 		}
 	}
 }
diff --git a/symbol.c b/symbol.c
index 046857b..8f4797a 100644
--- a/symbol.c
+++ b/symbol.c
@@ -47,9 +47,9 @@ getsym(Rune *name, int fresh)
 	tab->syms = erealloc(tab->syms, sizeof(Symbol *) * tab->nsyms);
 	tab->syms[tab->nsyms-1] = emalloc(sizeof(Symbol));
 	tab->syms[tab->nsyms-1]->name = runestrdup(name);
-	tab->syms[tab->nsyms-1]->undefined = 1;
 	tab->syms[tab->nsyms-1]->getfn = nil;
 	tab->syms[tab->nsyms-1]->setfn = nil;
+	tab->syms[tab->nsyms-1]->value = nil;
 	return tab->syms[tab->nsyms-1];
 }
 
@@ -71,8 +71,7 @@ freesymtab(Symtab *tab)
 	int i;
 	for(i = 0; i < tab->nsyms; i++){
 		Symbol *s = tab->syms[i];
-		if(s->undefined == 0)
-			freedatum(s->value);
+		freedatum(s->value);
 		free(s->name);
 	}
 	free(tab->syms);
@@ -87,22 +86,18 @@ initsymtab(void)
 	s = getsym(L"⍺", 1);
 	s->getfn = getalpha;
 	s->setfn = setalpha;
-	s->undefined = 0;
 
 	s = getsym(L"⍵", 1);
 	s->getfn = getomega;
 	s->setfn = setsyntaxerr;
-	s->undefined = 0;
 
 	s = getsym(L"⍶", 1);
 	s->getfn = getalphao;
 	s->setfn = setsyntaxerr;
-	s->undefined = 0;
 
 	s = getsym(L"⍹", 1);
 	s->getfn = getomegao;
 	s->setfn = setsyntaxerr;
-	s->undefined = 0;
 }
 
 DfnFrame *
-- 
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