[r2003-10-10 22:00:14 by cvscast] Logical operators + regexp example

Original author: cvscast
Date: 2003-10-10 22:00:15+00:00

CHANGES

@@ -3,6 +3,7 @@
   * -o option for compilation
   * .cd suffixes are now optional in command line
   * Bugfixes
+  * Add logical operators &&, ||, and not
 
 0.2.0
   * Code upgraded to Ocaml 3.07+beta2

parser/ast.ml

@@ -43,6 +43,7 @@ and pexpr =
   | Abstraction of abstr
       
   (* Data constructors *)
+  | Const of Types.Const.t
   | Integer of Intervals.V.t
   | Char of Chars.V.t
   | Pair of pexpr * pexpr

parser/parser.ml

@@ -51,7 +51,7 @@ let tuple_queue =
 let char = mknoloc (Internal (Types.char Chars.any))
 let string_regexp = Star (Elem char)
 	       
-let cst_nil =  Atom (U.mk "nil")
+let cst_nil =  Const (Types.Atom (Atoms.V.mk_ascii "nil"))
 let pat_nil = mknoloc (Internal (Sequence.nil_type))
 		 
 let seq_of_string s =
@@ -171,6 +171,7 @@ EXTEND
 	| "transform" | "fun" | "in"
 	| "let" | "type" | "debug" | "include"
         | "and" | "validate" | "schema" | "namespace" | "ref" | "using"
+	| "not"
 	]
 	-> a
     ]
@@ -207,6 +208,11 @@ EXTEND
 	exp loc (Match (e1, [pat_nil,e2]))
     | "ref"; p = pat; e = expr ->
 	exp loc (Ref (e,p))
+    | "not"; e = expr ->
+	let p1 = mknoloc (Internal true_type)
+	and p2 = mknoloc (Internal false_type) in
+	exp loc (Match (e, [p1,Const (Types.Atom (false_atom)); 
+			     p2,Const (Types.Atom (true_atom))]))       
     ]
     |
     [ e1 = expr; ":="; e2 = expr ->
@@ -224,11 +230,19 @@ EXTEND
     | 
     [ e1 = expr; op = ["+" | "-" | "@" ]; e2 = expr -> 
 	exp loc (Op (op,[e1;e2]))
+    | e1 = expr; "||"; e2 = expr ->
+	let p1 = mknoloc (Internal true_type)
+	and p2 = mknoloc (Internal false_type) in
+	exp loc (Match (e1, [p1,Const (Types.Atom (true_atom)); p2,e2]))       
     | e = expr; "\\"; l = [IDENT | keyword ] -> 
 	exp loc (RemoveField (e, label l)) 
     ]
     |
     [ e1 = expr; op = ["*"]; e2 = expr -> exp loc (Op (op,[e1;e2]))  
+    | e1 = expr; "&&"; e2 = expr ->
+	let p1 = mknoloc (Internal true_type)
+	and p2 = mknoloc (Internal false_type) in
+	exp loc (Match (e1, [p1,e2;p2,Const (Types.Atom (false_atom))]))       
     | e = expr; op = "/"; p = pat ->
 
 	let tag = mk loc (Internal (Types.atom (Atoms.any))) in

parser/ulexer.ml

@@ -74,7 +74,7 @@ let rec token = lexer
      return lexbuf ("INT", L.utf8_lexeme lexbuf)
  | [ "<>=.,:;+-*/@&{}[]()|?`!" ]
  | "->" | "::" | ";;" | "--" | ":=" | "\\" | "++"
- | "{|" | "|}" | "<=" | ">=" | "<<" | ">>"
+ | "{|" | "|}" | "<=" | ">=" | "<<" | ">>" | "||" | "&&"
  | ["?+*"] "?" | "#" ->
      return lexbuf ("", L.utf8_lexeme lexbuf)
  | "#" ncname -> 

typing/typer.ml

@@ -146,6 +146,7 @@ let rec const env loc = function
   | Atom t -> Types.Atom (parse_atom env loc t)
   | Integer i -> Types.Integer i
   | Char c -> Types.Char c
+  | Const c -> c
   | _ -> raise_loc_generic loc "This should be a scalar or structured constant"
 
 (* I. Transform the abstract syntax of types and patterns into
@@ -821,7 +822,7 @@ let rec expr env loc = function
 		  Typed.fun_fv = fv
 		} in
       exp loc fv e
-  | (Integer _ | Char _ | Atom _) as c -> 
+  | (Integer _ | Char _ | Atom _ | Const _) as c -> 
       exp loc Fv.empty (Typed.Cst (const env loc c))
   | Pair (e1,e2) ->
       let (fv1,e1) = expr env loc e1 and (fv2,e2) = expr env loc e2 in

web/examples.xml

@@ -37,6 +37,24 @@ A detailed explanation of the code can be found <a href="tutorial_overloading.ht
 </sample>
 </box>
 
+<box title="Datatypes + first-class functions" link="data">
+<p>
+The program below shows how to simulate ML data types in CDuce.
+It implements a (naive backtracking) regular expression recognizer.
+The examples also demonstrate the use of first-class functions
+(used as continuations).
+</p>
+<p>
+Exercise for the reader: show that the algorithm may not terminate for 
+some special regular expressions.
+</p>
+<sample highlight="false">
+<include-verbatim file="regexp.cd"/>
+</sample>
+</box>
+
+
+
 <box title="The script that generates this site" link="site">
 <p>
 The script below is one of the longest CDuce application ever written

web/manual/expressions.xml

@@ -368,6 +368,14 @@ match %%e1%% with `true -> %%e2%% | `false -> %%e3%%
 <p>
 Note that the else-clause is mandatory.
 </p>
+
+<p>
+The infix operators <code>||</code> and <code>&amp;&amp;</code>
+denote respectively the logical or and the logical and. The prefix
+operator <code>not</code> denotes the logical negation.
+</p>
+
+
 </box>
 
 <box title="Upward coercions" link="upward">

web/memento.xml

@@ -55,6 +55,8 @@ _" character,  starting by a capitalized letter or underscore.</li>
      <br/> <code>+,*,-,div,mod</code> : Integer,Integer -> Integer
      <br/> <code>=, &lt;&lt;, &lt;=, &gt;&gt;, &gt;= </code> :
  <i>t</i>,<i>t</i> -> Bool = <code>`true | `false</code> (any non functional type <i>t</i>)
+     <br/> <code>||, &amp;&amp;</code> : Bool,Bool -> Bool
+     <br/> <code>not</code>: Bool -> Bool
    </li>
    <li>Prefix:
         <br/><code>load_xml,load_html</code> : String -> Any,