https://github.com/akkartik/mu/blob/master/018constant.cc
 1 //: A few literal constants.
 2 
 3 :(scenarios load)  // use 'load' instead of 'run' in all scenarios in this layer
 4 
 5 :(before "End Mu Types Initialization")
 6 put(Type_ordinal, "literal-boolean", 0);
 7 
 8 //: 'true'
 9 
10 :(scenario true)
11 def main [
12   1:boolean <- copy true
13 ]
14 +parse:   ingredient: {true: "literal-boolean"}
15 
16 :(before "End Parsing reagent")
17 if (name == "true") {
18   if (type != NULL) {
19     raise << "'true' is a literal and can't take a type\n" << end();
20     return;
21   }
22   type = new type_tree("literal-boolean");
23   set_value(1);
24 }
25 
26 //: 'false'
27 
28 :(scenario false)
29 def main [
30   1:boolean <- copy false
31 ]
32 +parse:   ingredient: {false: "literal-boolean"}
33 
34 :(before "End Parsing reagent")
35 if (name == "false") {
36   if (type != NULL) {
37     raise << "'false' is a literal and can't take a type\n" << end();
38     return;
39   }
40   type = new type_tree("literal-boolean");
41   set_value(0);
42 }
43 
44 //: 'null'
45 
46 :(before "End Mu Types Initialization")
47 put(Type_ordinal, "literal-address", 0);
48 
49 :(scenario null)
50 def main [
51   1:address:number <- copy null
52 ]
53 +parse:   ingredient: {null: "literal-address"}
54 
55 :(before "End Parsing reagent")
56 if (name == "null") {
57   if (type != NULL) {
58     raise << "'null' is a literal and can't take a type\n" << end();
59     return;
60   }
61   type = new type_tree("literal-address");
62   set_value(0);
63 }