Bug fixing in the AST pretty-printer and new syntax for iterators.

I added a type annotation for the variable iterating a
collection, which is also now marked as "map", "set" or "list".

I fixed and refactored the pretty-printer for the AST.

src/passes/1-parser/pascaligo/AST.ml

@@ -438,11 +438,19 @@ and for_collect = {
   kwd_for    : kwd_for;
   var        : variable;
   bind_to    : (arrow * variable) option;
+  colon      : colon;
+  elt_type   : type_expr;
   kwd_in     : kwd_in;
+  collection : collection;
   expr       : expr;
   block      : block reg
 }
 
+and collection =
+  Map  of kwd_map
+| Set  of kwd_set
+| List of kwd_list
+
 (* Expressions *)
 
 and expr =

src/passes/1-parser/pascaligo/AST.mli

@@ -422,11 +422,19 @@ and for_collect = {
   kwd_for    : kwd_for;
   var        : variable;
   bind_to    : (arrow * variable) option;
+  colon      : colon;
+  elt_type   : type_expr;
   kwd_in     : kwd_in;
+  collection : collection;
   expr       : expr;
   block      : block reg
 }
 
+and collection =
+  Map  of kwd_map
+| Set  of kwd_set
+| List of kwd_list
+
 (* Expressions *)
 
 and expr =

src/passes/1-parser/pascaligo/Parser.mly

@@ -630,17 +630,26 @@ for_loop:
       block   = $5}
     in For (ForInt {region; value})
   }
-| For var option(arrow_clause) In expr block {
-    let region = cover $1 $6.region in
+| For var option(arrow_clause) COLON type_expr
+  In collection expr block {
+    let region = cover $1 $9.region in
     let value = {
       kwd_for    = $1;
       var        = $2;
       bind_to    = $3;
-      kwd_in  = $4;
-      expr    = $5;
-      block   = $6}
+      colon      = $4;
+      elt_type   = $5;
+      kwd_in     = $6;
+      collection = $7;
+      expr       = $8;
+      block      = $9}
     in For (ForCollect {region; value})}
 
+collection:
+  Map  { Map  $1 }
+| Set  { Set  $1 }
+| List { List $1 }
+
 var_assign:
   var ASS expr {
     let region = cover $1.region (expr_to_region $3)