Add lib/std, compile_expression ()
diff --git a/src/lisp/lib/std.c b/src/lisp/lib/std.c
new file mode 100644
index 0000000..35226da
--- /dev/null
+++ b/src/lisp/lib/std.c
@@ -0,0 +1,28 @@
+#include "std.h"
+
+value_t l_plus (value_t a, value_t b)
+{
+ if ( !integerp (a) || !integerp (b) )
+ return nil;
+
+ return (((a >> 2) + (b >> 2)) << 2) | INT_TAG;
+}
+
+void add_function (struct environment *env, char *name, void *func, int nargs)
+{
+ struct function *last,
+ *new = malloc (sizeof (struct function));
+
+ last = env->first;
+ new->prev = last;
+ new->name = name;
+ new->nargs = nargs;
+ new->code_ptr = func;
+
+ env->prev = new;
+}
+
+void load_std (struct environment *env)
+{
+ add_function (env, "+", l_plus, 2);
+}