Boolean literals.

aktemur · Nov 6, 2017 · d45eec2 · d45eec2
1 parent 2883904
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diff --git a/Deve/README.md b/Deve/README.md
@@ -14,6 +14,7 @@ Grammar:
 ```
 main ::= exp EOF
 exp  ::= INT
+       | BOOL
        | NAME
        | LET NAME EQUALS exp IN exp
 ```
@@ -82,5 +83,9 @@ Sample run:
 # parse "let x = let y = z in 42 in let f = 8 in 7";;
 - : exp =
 LetIn ("x", LetIn ("y", Var "z", CstI 42), LetIn ("f", CstI 8, CstI 7))
+# parse "true";;
+- : exp = CstB true
+# parse "false";;
+- : exp = CstB false
 ```
 
diff --git a/Deve/lexer.ml b/Deve/lexer.ml
@@ -6,6 +6,7 @@
    "a name", etc.
  *)
 type token = INT of int
+           | BOOL of bool
            | NAME of string
            | PLUS | STAR | MINUS | SLASH
            | LET | EQUALS | IN
@@ -33,6 +34,8 @@ let keyword s =
   | "if" -> IF
   | "then" -> THEN
   | "else" -> ELSE
+  | "true" -> BOOL true
+  | "false" -> BOOL false
   | _ -> NAME s
 
 (*  tokenize: char list -> token list  *)

diff --git a/Deve/parser.ml b/Deve/parser.ml
@@ -5,6 +5,7 @@
 let rec parseExp tokens =
   match tokens with
   | INT i :: rest -> (CstI i, rest)
+  | BOOL b :: rest -> (CstB b, rest)
   | NAME x :: rest -> (Var x, rest)
   | LET::(NAME x)::EQUALS::rest ->
      (match parseExp rest with