configurable none value

include/config.h

@@ -10,6 +10,9 @@
 /* enable readline module */
 #define PIC_ENABLE_READLINE 1
 
+/* treat false value as none */
+#define PIC_NONE_IS_FALSE 1
+
 /* initial memory size (to be dynamically extended if necessary) */
 #define PIC_ARENA_SIZE 100
 #define PIC_HEAP_PAGE_SIZE (10000)

include/picrin/value.h

@@ -143,6 +143,7 @@ pic_value pic_float_value(double);
 pic_value pic_int_value(int);
 pic_value pic_symbol_value(pic_sym);
 pic_value pic_char_value(char c);
+pic_value pic_none_value();
 
 #define pic_float(v) ((v).u.f)
 #define pic_int(v) ((v).u.i)

src/blob.c

@@ -76,7 +76,7 @@ pic_blob_bytevector_u8_set(pic_state *pic)
     pic_error(pic, "byte out of range");
 
   bv->data[k] = v;
-  return pic_false_value();
+  return pic_none_value();
 }
 
 void

src/codegen.c

@@ -8,6 +8,12 @@
 #include "picrin/macro.h"
 #include "xhash/xhash.h"
 
+#if PIC_NONE_IS_FALSE
+# define OP_PUSHNONE OP_PUSHFALSE
+#else
+# error enable PIC_NONE_IS_FALSE
+#endif
+
 #define FALLTHROUGH ((void)0)
 
 typedef struct codegen_scope {
@@ -272,7 +278,7 @@ codegen(codegen_state *state, pic_value obj, bool tailpos)
 	  irep->code[irep->clen].insn = OP_GSET;
 	  irep->code[irep->clen].u.i = idx;
 	  irep->clen++;
-	  irep->code[irep->clen].insn = OP_PUSHFALSE;
+	  irep->code[irep->clen].insn = OP_PUSHNONE;
 	  irep->clen++;
 	  break;
 	}
@@ -283,7 +289,7 @@ codegen(codegen_state *state, pic_value obj, bool tailpos)
 	  irep->code[irep->clen].u.r.depth = 0;
 	  irep->code[irep->clen].u.r.idx = idx;
 	  irep->clen++;
-	  irep->code[irep->clen].insn = OP_PUSHFALSE;
+	  irep->code[irep->clen].insn = OP_PUSHNONE;
 	  irep->clen++;
 	  break;
 	}
@@ -312,7 +318,7 @@ codegen(codegen_state *state, pic_value obj, bool tailpos)
 	int s,t;
 	pic_value if_true, if_false;
 
-	if_false = pic_false_value();
+	if_false = pic_none_value();
 	switch (pic_length(pic, obj)) {
 	default:
 	  pic_error(pic, "syntax error");
@@ -400,7 +406,7 @@ codegen(codegen_state *state, pic_value obj, bool tailpos)
 	  break;
 	}
 
-	irep->code[irep->clen].insn = OP_PUSHFALSE;
+	irep->code[irep->clen].insn = OP_PUSHNONE;
 	irep->clen++;
 	break;
       }

src/file.c

@@ -99,7 +99,7 @@ pic_file_delete(pic_state *pic)
   if (remove(fname) != 0) {
     pic_error(pic, "file cannot be deleted");
   }
-  return pic_true_value();
+  return pic_none_value();
 }
 
 void

src/macro.c

@@ -297,7 +297,7 @@ macroexpand(pic_state *pic, pic_value expr, struct pic_senv *senv)
         }
         pic_in_library(pic, prev->name);
 
-        return pic_false_value();
+        return pic_none_value();
       }
       case PIC_STX_IMPORT: {
         struct pic_lib *lib;
@@ -339,7 +339,7 @@ macroexpand(pic_state *pic, pic_value expr, struct pic_senv *senv)
             xh_next(lib->exports, &it);
           }
         }
-        return pic_false_value();
+        return pic_none_value();
       }
       case PIC_STX_EXPORT: {
         for (v = pic_cdr(pic, expr); ! pic_nil_p(v); v = pic_cdr(pic, v)) {
@@ -350,7 +350,7 @@ macroexpand(pic_state *pic, pic_value expr, struct pic_senv *senv)
           /* TODO: warn if symbol is shadowed by local variable */
           pic_export(pic, pic_sym(spec));
         }
-        return pic_false_value();
+        return pic_none_value();
       }
       case PIC_STX_DEFSYNTAX: {
 	pic_value var, val;
@@ -380,7 +380,7 @@ macroexpand(pic_state *pic, pic_value expr, struct pic_senv *senv)
 	pic_defsyntax(pic, pic_symbol_name(pic, pic_sym(var)), pic_proc_ptr(v), senv);
 
 	pic_gc_arena_restore(pic, ai);
-	return pic_false_value();
+	return pic_none_value();
       }
       case PIC_STX_DEFMACRO: {
 	pic_value var, val;
@@ -422,7 +422,7 @@ macroexpand(pic_state *pic, pic_value expr, struct pic_senv *senv)
 	pic_defmacro(pic, pic_symbol_name(pic, pic_sym(var)), pic_proc_ptr(v));
 
 	pic_gc_arena_restore(pic, ai);
-	return pic_false_value();
+	return pic_none_value();
       }
       case PIC_STX_MACRO: {
 	if (pic_syntax(car)->senv == NULL) { /* legacy macro */

src/pair.c

@@ -237,7 +237,7 @@ pic_pair_set_car(pic_state *pic)
     pic_error(pic, "pair expected");
 
   pic_pair_ptr(v)->car = w;
-  return pic_true_value();
+  return pic_none_value();
 }
 
 static pic_value
@@ -251,7 +251,7 @@ pic_pair_set_cdr(pic_state *pic)
     pic_error(pic, "pair expected");
 
   pic_pair_ptr(v)->cdr = w;
-  return pic_true_value();
+  return pic_none_value();
 }
 
 void

src/port.c

@@ -263,14 +263,14 @@ pic_port_write(pic_state *pic)
 
   pic_get_args(pic, "o", &v);
   write(pic, v);
-  return pic_false_value();
+  return pic_none_value();
 }
 
 static pic_value
 pic_port_newline(pic_state *pic)
 {
   puts("");
-  return pic_false_value();
+  return pic_none_value();
 }
 
 static pic_value
@@ -318,7 +318,7 @@ pic_port_close_port(pic_state *pic)
   }
   port->status = PIC_PORT_CLOSE;
 
-  return pic_false_value();
+  return pic_none_value();
 }
 
 void

src/string.c

@@ -82,7 +82,7 @@ pic_str_string_set(pic_state *pic)
   pic_get_args(pic, "sic", &str, &len, &k, &c);
 
   str[k] = c;
-  return pic_false_value();
+  return pic_none_value();
 }
 
 #define DEFINE_STRING_CMP(name, op)			\

src/value.c

@@ -208,6 +208,16 @@ pic_undef_value()
   return v;
 }
 
+pic_value
+pic_none_value()
+{
+#if PIC_NONE_IS_FALSE
+  return pic_false_value();
+#else
+# error enable PIC_NONE_IS_FALSE
+#endif
+}
+
 #if PIC_NAN_BOXING
 
 bool

src/vector.c

@@ -11,7 +11,7 @@ pic_vec_new(pic_state *pic, size_t len)
   vec->len = len;
   vec->data = (pic_value *)pic_alloc(pic, sizeof(pic_value) * len);
   for (i = 0; i < len; ++i) {
-    vec->data[i] = pic_false_value();
+    vec->data[i] = pic_none_value();
   }
   return vec;
 }
@@ -41,7 +41,7 @@ pic_vec_extend_ip(pic_state *pic, struct pic_vector *vec, int size)
   vec->len = size;
   vec->data = (pic_value *)pic_realloc(pic, vec->data, sizeof(pic_value) * size);
   for (i = len; i < size; ++i) {
-    vec->data[i] = pic_false_value();
+    vec->data[i] = pic_none_value();
   }
 }
 
@@ -110,7 +110,7 @@ pic_vec_vector_set(pic_state *pic)
     pic_error(pic, "vector-set!: index out of range");
   }
   v->data[k] = o;
-  return pic_false_value();
+  return pic_none_value();
 }
 
 void