Add some library functions and add newline character to reading line

from file.

src/compiler/boot.dst

@@ -130,3 +130,33 @@
 
 (fn [x] (print (pp1 @{} @"" x)))
 ))
+
+(defn pairs [x]
+ (var lastkey (next x nil))
+ {
+    :more (fn [] lastkey)
+    :next (fn []
+        (def ret (tuple lastkey (get x lastkey)))
+        (varset! lastkey (next x lastkey))
+        ret)
+ })
+
+(defn keys [x]
+ (var lastkey (next x nil))
+ {
+    :more (fn [] lastkey)
+    :next (fn []
+        (def ret lastkey)
+        (varset! lastkey (next x lastkey))
+        ret)
+ })
+
+(defn values [x]
+ (var lastkey (next x nil))
+ {
+    :more (fn [] lastkey)
+    :next (fn []
+        (def ret (get x lastkey))
+        (varset! lastkey (next x lastkey))
+        ret)
+ })

src/core/io.c

@@ -187,10 +187,8 @@ static int dst_io_fread(DstArgs args) {
         } else if (!dst_cstrcmp(sym, ":line")) {
             for (;;) {
                 int x = fgetc(iof->file);
-                if (x == EOF || x == '\n') {
+                if (x != EOF && dst_buffer_push_u8(b, (uint8_t)x)) return dst_throw(args, "buffer overflow");
-                    break;
+                if (x == EOF || x == '\n') break;
-                }
-                if (dst_buffer_push_u8(b, (uint8_t)x)) return dst_throw(args, "buffer overflow");
             }
             return dst_return(args, dst_wrap_buffer(b));
         } else {