Add the tiger source code bundle from the book site

Signed-off-by: jmug <u.g.a.mariano@gmail.com>

tiger/chap4/tiger.grm

@@ -0,0 +1,40 @@
+structure A = Absyn
+
+%%
+%term
+    EOF 
+  | ID of string
+  | INT of int | STRING of string 
+  | COMMA | COLON | SEMICOLON | LPAREN | RPAREN | LBRACK | RBRACK 
+  | LBRACE | RBRACE | DOT 
+  | PLUS | MINUS | TIMES | DIVIDE | EQ | NEQ | LT | LE | GT | GE
+  | AND | OR | ASSIGN
+  | ARRAY | IF | THEN | ELSE | WHILE | FOR | TO | DO | LET | IN | END | OF 
+  | BREAK | NIL
+  | FUNCTION | VAR | TYPE 
+
+%nonterm  exp | program of A.exp
+
+%pos int
+%verbose
+%start program
+%eop EOF
+%noshift EOF
+
+%name Tiger
+
+%keyword WHILE FOR TO BREAK LET IN END FUNCTION VAR TYPE ARRAY IF THEN ELSE 
+	DO OF NIL
+
+%prefer THEN ELSE LPAREN
+
+%value ID ("bogus")
+%value INT (1)
+%value STRING ("")
+
+%%
+
+program	: exp				(exp)
+
+	
+exp: NIL		(A.NilExp)