Fix typo

chapters/3_rewriting.tex

@@ -104,7 +104,7 @@ and where expressions have \mzninline{par} type.
     \alt "let" "{" <item>* "}" "in" <literal>
     \alt "if" <exp> "then" <exp> "else" <exp> "endif"
     \alt "[" <exp> "|" <gen-exp> "where" <exp> "]"
-    \lat <ident>"[" <literal> "]"
+    \alt <ident>"[" <literal> "]"
 
     <item> ::= <param> [ "=" <exp> ]";"
     \alt "tuple(" <type-inst> ["," <type-inst>]* "):" <ident> = "(" <exp> ["," <exp>]* ")";