Selections can be done now through tuples.

New syntax: a.2.b.4.2.x
where the numerals denote the component of a tuple.

AST.ml

@@ -505,6 +505,7 @@ and expr =
 | ESet    of set_expr
 | EConstr of constr_expr
 | ERecord of record_expr
+| EProj   of projection reg
 | EMap    of map_expr
 | EVar    of Lexer.lexeme reg
 | ECall   of fun_call
@@ -543,7 +544,7 @@ and map_lookup = {
 
 and path =
   Name of variable
-| RecordPath of record_projection reg
+| Path of projection reg
 
 and logic_expr =
   BoolExpr of bool_expr
@@ -613,7 +614,6 @@ and constr_expr =
 
 and record_expr =
   RecordInj of record_injection reg
-| RecordProj of record_projection reg
 
 and record_injection = {
   opening    : kwd_record;
@@ -628,12 +628,16 @@ and field_assign = {
   field_expr : expr
 }
 
-and record_projection = {
+and projection = {
   record_name : variable;
   selector    : dot;
-  field_path  : (field_name, dot) nsepseq
+  field_path  : (selection, dot) nsepseq
 }
 
+and selection =
+  FieldName of field_name
+| Component of (Lexer.lexeme * Z.t) reg
+
 and tuple_expr =
   TupleInj  of tuple_injection
 
@@ -694,6 +698,7 @@ let rec expr_to_region = function
 | ERecord e -> record_expr_to_region e
 | EMap    e -> map_expr_to_region e
 | ETuple  e -> tuple_expr_to_region e
+| EProj  {region; _}
 | EVar   {region; _}
 | ECall  {region; _}
 | EBytes {region; _}
@@ -754,12 +759,11 @@ and constr_expr_to_region = function
 | SomeApp   {region; _} -> region
 
 and record_expr_to_region = function
-  RecordInj  {region; _}
-| RecordProj {region; _} -> region
+  RecordInj  {region; _} -> region
 
 let path_to_region = function
   Name var -> var.region
-| RecordPath {region; _} -> region
+| Path {region; _} -> region
 
 let instr_to_region = function
   Single Cond                {region; _}
@@ -805,7 +809,7 @@ let local_decl_to_region = function
 | LocalConst         {region; _}
 | LocalVar           {region; _} -> region
 
-let lhs_to_region = function
+let lhs_to_region : lhs -> Region.t = function
   Path path -> path_to_region path
 | MapPath {region; _} -> region
 
@@ -813,6 +817,10 @@ let rhs_to_region = function
       Expr e -> expr_to_region e
 | NoneExpr r -> r
 
+let selection_to_region = function
+  FieldName {region; _}
+| Component {region; _} -> region
+
 (* Printing the tokens with their source regions *)
 
 let printf = Printf.printf
@@ -1215,6 +1223,7 @@ and print_expr = function
 | ESet    e -> print_set_expr e
 | EConstr e -> print_constr_expr e
 | ERecord e -> print_record_expr e
+| EProj   e -> print_projection e
 | EMap    e -> print_map_expr e
 | EVar    v -> print_var v
 | ECall   e -> print_fun_call e
@@ -1246,7 +1255,7 @@ and print_map_lookup {path; index} =
 
 and print_path = function
   Name var  -> print_var var
-| RecordPath path -> print_record_projection path
+| Path path -> print_projection path
 
 and print_logic_expr = function
   BoolExpr e -> print_bool_expr e
@@ -1309,7 +1318,6 @@ and print_constr_expr = function
 
 and print_record_expr = function
   RecordInj e -> print_record_injection e
-| RecordProj e -> print_record_projection e
 
 and print_record_injection {value; _} =
   let {opening; fields; terminator; closing} = value in
@@ -1324,14 +1332,18 @@ and print_field_assign {value; _} =
   print_token equal "=";
   print_expr field_expr
 
-and print_record_projection {value; _} =
+and print_projection {value; _} =
   let {record_name; selector; field_path} = value in
   print_var record_name;
   print_token selector ".";
   print_field_path field_path
 
 and print_field_path sequence =
-  print_nsepseq "." print_var sequence
+  print_nsepseq "." print_selection sequence
+
+and print_selection = function
+  FieldName name -> print_var name
+| Component int  -> print_int int
 
 and print_record_patch node =
   let {kwd_patch; path; kwd_with; record_inj} = node in

AST.mli

@@ -489,6 +489,7 @@ and expr =
 | ESet    of set_expr
 | EConstr of constr_expr
 | ERecord of record_expr
+| EProj   of projection reg
 | EMap    of map_expr
 | EVar    of Lexer.lexeme reg
 | ECall   of fun_call
@@ -527,7 +528,7 @@ and map_lookup = {
 
 and path =
   Name of variable
-| RecordPath of record_projection reg
+| Path of projection reg
 
 and logic_expr =
   BoolExpr of bool_expr
@@ -597,7 +598,6 @@ and constr_expr =
 
 and record_expr =
   RecordInj of record_injection reg
-| RecordProj of record_projection reg
 
 and record_injection = {
   opening    : kwd_record;
@@ -612,12 +612,16 @@ and field_assign = {
   field_expr : expr
 }
 
-and record_projection = {
+and projection = {
   record_name : variable;
   selector    : dot;
-  field_path  : (field_name, dot) nsepseq
+  field_path  : (selection, dot) nsepseq
 }
 
+and selection =
+  FieldName of field_name
+| Component of (Lexer.lexeme * Z.t) reg
+
 and tuple_expr =
   TupleInj  of tuple_injection
 
@@ -667,6 +671,7 @@ val path_to_region       : path -> Region.t
 val lhs_to_region        : lhs -> Region.t
 val rhs_to_region        : rhs -> Region.t
 val if_clause_to_region  : if_clause -> Region.t
+val selection_to_region  : selection -> Region.t
 
 (* Printing *)
 

Parser.mly

@@ -936,6 +936,7 @@ core_expr:
 | fun_call         { ECall $1 }
 | map_expr         { EMap $1 }
 | record_expr      { ERecord $1 }
+| projection       { EProj $1 }
 | Constr arguments {
     let region = cover $1.region $2.region in
     EConstr (ConstrApp {region; value = $1,$2})
@@ -948,20 +949,32 @@ core_expr:
 map_expr:
   map_lookup { MapLookUp $1 }
 
-path:
-  var               {       Name $1 }
-| record_projection { RecordPath $1 }
-
 map_lookup:
   path brackets(expr) {
     let region = cover (path_to_region $1) $2.region in
     let value  = {path=$1; index=$2}
-    in {region; value}
-  }
+    in {region; value}}
+
+path:
+  var        { Name $1 }
+| projection { Path $1 }
 
 record_expr:
   record_injection { RecordInj $1 }
-| record_projection { RecordProj $1 }
+
+projection:
+  record_name DOT nsepseq(selection,DOT) {
+    let stop   = nsepseq_to_region selection_to_region $3 in
+    let region = cover $1.region stop
+    and value  = {
+      record_name = $1;
+      selector    = $2;
+      field_path  = $3}
+    in {region; value}}
+
+selection:
+  field_name { FieldName $1 }
+| Int        { Component $1 }
 
 record_injection:
   Record series(field_assignment,End) {
@@ -972,8 +985,7 @@ record_injection:
       fields  = first, others;
       terminator;
       closing}
-    in {region; value}
-  }
+    in {region; value}}
 
 field_assignment:
   field_name EQUAL expr {
@@ -985,17 +997,6 @@ field_assignment:
     in {region; value}
   }
 
-record_projection:
-  record_name DOT nsepseq(field_name,DOT) {
-    let stop   = nsepseq_to_region (fun x -> x.region) $3 in
-    let region = cover $1.region stop
-    and value  = {
-      record_name = $1;
-      selector    = $2;
-      field_path  = $3}
-    in {region; value}
-  }
-
 fun_call:
   fun_name arguments {
     let region = cover $1.region $2.region
@@ -1050,8 +1051,7 @@ list_expr:
       elements   = None;
       terminator = None;
       closing    = RBracket $3}
-    in {region; value}
-  }
+    in {region; value}}
 
 nil:
   par(typed_empty_list) { $1 }
@@ -1060,8 +1060,7 @@ typed_empty_list:
   Nil COLON type_expr {
     {nil       = $1;
      colon     = $2;
-     list_type = $3}
-  }
+     list_type = $3}}
 
 none_expr:
   par(typed_none_expr) { $1 }
@@ -1070,8 +1069,7 @@ typed_none_expr:
   C_None COLON type_expr {
     {c_None   = $1;
      colon    = $2;
-     opt_type = $3}
-  }
+     opt_type = $3}}
 
 (* Patterns *)
 
@@ -1094,8 +1092,7 @@ core_pattern:
 | tuple_patt {  PTuple $1 }
 | C_Some par(core_pattern) {
     let region = cover $1 $2.region
-    in PSome {region; value = $1,$2}
-  }
+    in PSome {region; value = $1,$2}}
 
 list_patt:
   brackets(sepseq(core_pattern,COMMA)) { Sugar $1 }