can read and print doubles

src/obj.c

@@ -41,6 +41,12 @@ Obj *obj_new_float(float x) {
   return o;
 }
 
+Obj *obj_new_double(double x) {
+  Obj *o = obj_new('W');
+  o->f64 = x;
+  return o;
+}
+
 Obj *obj_new_string(char *s) {
   Obj *o = obj_new('S');
   o->s = strdup(s);

src/obj.h

@@ -89,6 +89,8 @@ typedef struct Obj {
     void *void_ptr;
     // Float
     float f32;
+    // Double
+    double f64;
     // Char
     char character;
     // Bool
@@ -108,6 +110,7 @@ typedef Obj* (*Primop)(Obj**, int);
 Obj *obj_new_cons(Obj *car, Obj *cdr);
 Obj *obj_new_int(int i);
 Obj *obj_new_float(float x);
+Obj *obj_new_double(double x);
 Obj *obj_new_string(char *s);
 Obj *obj_new_symbol(char *s);
 Obj *obj_new_keyword(char *s);

src/obj_string.c

@@ -207,6 +207,12 @@ void obj_to_string_internal(Obj *total, const Obj *o, bool prn, int indent) {
     snprintf(temp, 64, "%f", o->f32);
     obj_string_mut_append(total, temp);
   }
+  else if(o->tag == 'W') {
+    static char temp[64];
+    snprintf(temp, 64, "%f", o->f64);
+    obj_string_mut_append(total, temp);
+    obj_string_mut_append(total, "d");
+  }
   else if(o->tag == 'S') {
     if(prn) {
       obj_string_mut_append(total, "\"");

src/reader.c

@@ -190,6 +190,7 @@ Obj *read_internal(Obj *env, char *s, Obj *filename) {
       read_pos++;
     }
     bool is_floating = false;
+    bool is_double = false;
     char scratch[32];
     int i = 0;
     while(isdigit(CURRENT)) {
@@ -205,14 +206,26 @@ Obj *read_internal(Obj *env, char *s, Obj *filename) {
 	read_pos++;
 	break;
       }
+      if(CURRENT == 'd') {
+	is_double = true;
+	read_pos++;
+	break;
+      }
     }
     scratch[i] = '\0';
-    if(is_floating) {
+    if(is_double) {
+      double x = atof(scratch) * negator;
+      Obj *new_double = obj_new_double(x);
+      obj_set_line_info(new_double, line, pos, filename);
+      return new_double;
+    } 
+    else if(is_floating) {
       float x = (float)atof(scratch) * negator;
       Obj *new_float = obj_new_float(x);
       obj_set_line_info(new_float, line, pos, filename);
       return new_float;
-    } else {
+    }
+    else {
       int num = atoi(scratch) * negator;
       Obj *new_int = obj_new_int(num);
       obj_set_line_info(new_int, line, pos, filename);