From 8ba3fa08609697a0ab63ddfc278b1025b3062481 Mon Sep 17 00:00:00 2001
From: Jesse McDonald <nybble41@gmail.com>
Date: Fri, 6 Jul 2012 10:51:27 -0500
Subject: [PATCH] Add built-in functions to exit the program and format floats
 as strings.

---
 builtin.c | 25 +++++++++++++++++++++++++
 builtin.h |  2 ++
 2 files changed, 27 insertions(+)

diff --git a/builtin.c b/builtin.c
index c9ecca7..0f74138 100644
--- a/builtin.c
+++ b/builtin.c
@@ -2,6 +2,7 @@
 #include <inttypes.h>
 #include <stdbool.h>
 #include <stdlib.h>
+#include <stdio.h>
 #include <math.h>
 
 #include "gc.h"
@@ -23,6 +24,8 @@ static void bi_display(interp_state_t *state);
 static void bi_register_finalizer(interp_state_t *state);
 static void bi_current_context(interp_state_t *state);
 static void bi_call_with_context(interp_state_t *state);
+static void bi_exit(interp_state_t *state);
+static void bi_float_to_string(interp_state_t *state);
 
 void builtin_init(void)
 {
@@ -58,6 +61,10 @@ void builtin_init(void)
 
   register_builtin(BI_CURRENT_CONTEXT,    make_builtin_fn(bi_current_context));
   register_builtin(BI_CALL_WITH_CONTEXT,  make_builtin_fn(bi_call_with_context));
+
+  register_builtin(BI_EXIT,               make_builtin_fn(bi_exit));
+
+  register_builtin(BI_FLOAT_TO_STRING,    make_builtin_fn(bi_float_to_string));
 }
 
 void register_builtin(const char *name, value_t value)
@@ -227,4 +234,22 @@ static void bi_call_with_context(interp_state_t *state)
   state->kw_vals.value = NIL;
 }
 
+static void bi_exit(interp_state_t *state)
+{
+  state->ctx.value     = NIL;
+  state->lambda.value  = END_PROGRAM;
+  state->kw_args.value = NIL;
+  state->kw_vals.value = NIL;
+}
+
+static void bi_float_to_string(interp_state_t *state)
+{
+  char buffer[32];
+  native_float_t flt = get_float(CAR(state->argv.value));
+
+  snprintf(buffer, sizeof buffer, "%.18g", (double)flt);
+
+  interp_return_values(state, cons(string_to_value(buffer), NIL));
+}
+
 /* vim:set sw=2 expandtab: */
diff --git a/builtin.h b/builtin.h
index a3bc97c..04927a4 100644
--- a/builtin.h
+++ b/builtin.h
@@ -28,6 +28,8 @@
 #define BI_DISPLAY             "display"
 #define BI_CURRENT_CONTEXT     "current-context"
 #define BI_CALL_WITH_CONTEXT   "call-with-context"
+#define BI_EXIT                "exit"
+#define BI_FLOAT_TO_STRING     "float->string"
 
 /* Lambda: Instances of this structure are fundamental callable objects. */
 #define LAMBDA_SLOT_GLOBAL_VARS   0