commit 3496656

Add Usage in README

 1@@ -6,3 +6,57 @@ larger configuration languages.
 2 
 3 For maximum compatibility, it's written in ANSI C.
 4 
 5+#### Usage
 6+An extract from `expl.c`:
 7+
 8+``` c
 9+static expl_value
10+birds_who_hit_my_window(int argc, const expl_value* argv, void* data)
11+{
12+	int* count = (int*)data;
13+	expl_value result = { 0 };
14+
15+	if (argc == 1 && argv[0].type == EXPL_VALUE_NUMBER)
16+		*count += (int)argv[0].as.number;
17+
18+	result.type = EXPL_VALUE_NUMBER;
19+	result.as.number = *count;
20+
21+	return result;
22+}
23+
24+#define FIND_THE_BIRDS \
25+"(fn foo (x) (birds_who_hit_window x))\n" \
26+"(foo 134)\n"
27+
28+int
29+main(void)
30+{
31+	int birds_who_hit_my_window_c = 0;
32+	expl* ctx = expl_init();
33+
34+	if (!ctx)
35+		return EXIT_FAILURE;
36+
37+	expl_register(ctx, "birds_who_hit_my_window", birds_who_hit_my_window, &birds_who_hit_my_window_c);
38+	expl_run(ctx, FIND_THE_BIRDS);
39+	printf("Stupid birds: %d\n", birds_who_hit_my_window_c);
40+
41+	expl_close(ctx);
42+	return EXIT_SUCCESS;
43+}
44+```
45+
46+And an `expl_value` is defined as:
47+
48+``` c
49+struct expl_value {
50+	expl_value_type type;
51+	union {
52+		double number;
53+		char*  string;
54+		void*  function;
55+	} as;
56+};
57+```
58+