for loop have a optional step parameter

src/bin/expect_tests/contract_tests.ml

@@ -1117,7 +1117,7 @@ let%expect_test _ =
 let%expect_test _ =
   run_ligo_bad [ "compile-contract" ; bad_contract "create_contract_toplevel.mligo" ; "main" ] ;
   [%expect {|
-ligo: in file "create_contract_toplevel.mligo", line 4, character 35 to line 8, character 8. No free variable allowed in this lambda: variable 'store' {"expression":"CREATE_CONTRACT(lambda (#P:Some(( nat * string ))) : None return\n                let rhs#712 = #P in\n                let p = rhs#712.0 in\n                let s = rhs#712.1 in\n                ( LIST_EMPTY() : (type_operator: list(operation)) , store ) ,\n                NONE() : (type_operator: option(key_hash)) ,\n                300000000mutez ,\n                \"un\")","location":"in file \"create_contract_toplevel.mligo\", line 4, character 35 to line 8, character 8"}
+ligo: in file "create_contract_toplevel.mligo", line 4, character 35 to line 8, character 8. No free variable allowed in this lambda: variable 'store' {"expression":"CREATE_CONTRACT(lambda (#P:Some(( nat * string ))) : None return\n                let rhs#713 = #P in\n                let p = rhs#713.0 in\n                let s = rhs#713.1 in\n                ( LIST_EMPTY() : (type_operator: list(operation)) , store ) ,\n                NONE() : (type_operator: option(key_hash)) ,\n                300000000mutez ,\n                \"un\")","location":"in file \"create_contract_toplevel.mligo\", line 4, character 35 to line 8, character 8"}
 
 
  If you're not sure how to fix this error, you can
@@ -1130,7 +1130,7 @@ ligo: in file "create_contract_toplevel.mligo", line 4, character 35 to line 8,
 
   run_ligo_bad [ "compile-contract" ; bad_contract "create_contract_var.mligo" ; "main" ] ;
   [%expect {|
-ligo: in file "create_contract_var.mligo", line 6, character 35 to line 10, character 5. No free variable allowed in this lambda: variable 'a' {"expression":"CREATE_CONTRACT(lambda (#P:Some(( nat * int ))) : None return\n                let rhs#715 = #P in\n                let p = rhs#715.0 in\n                let s = rhs#715.1 in\n                ( LIST_EMPTY() : (type_operator: list(operation)) , a ) ,\n                NONE() : (type_operator: option(key_hash)) ,\n                300000000mutez ,\n                1)","location":"in file \"create_contract_var.mligo\", line 6, character 35 to line 10, character 5"}
+ligo: in file "create_contract_var.mligo", line 6, character 35 to line 10, character 5. No free variable allowed in this lambda: variable 'a' {"expression":"CREATE_CONTRACT(lambda (#P:Some(( nat * int ))) : None return\n                let rhs#716 = #P in\n                let p = rhs#716.0 in\n                let s = rhs#716.1 in\n                ( LIST_EMPTY() : (type_operator: list(operation)) , a ) ,\n                NONE() : (type_operator: option(key_hash)) ,\n                300000000mutez ,\n                1)","location":"in file \"create_contract_var.mligo\", line 6, character 35 to line 10, character 5"}
 
 
  If you're not sure how to fix this error, you can

src/bin/expect_tests/misc_cli_commands.ml

@@ -13,7 +13,7 @@ let%expect_test _ =
 (* list-declarations *)
 let%expect_test _ =
   run_ligo_good [ "list-declarations" ; "../../test/contracts/loop.ligo" ] ;
-  [%expect {| {"source_file":"../../test/contracts/loop.ligo","declarations":["inner_capture_in_conditional_block","dummy","nested_for_collection_local_var","nested_for_collection","for_collection_map_k","for_collection_map_kv","for_collection_empty","for_collection_with_patches","for_collection_comp_with_acc","for_collection_proc_call","for_collection_rhs_capture","for_collection_if_and_local_var","for_collection_set","for_collection_list","for_sum","while_sum","counter"]} |} ];
+  [%expect {| {"source_file":"../../test/contracts/loop.ligo","declarations":["inner_capture_in_conditional_block","dummy","nested_for_collection_local_var","nested_for_collection","for_collection_map_k","for_collection_map_kv","for_collection_empty","for_collection_with_patches","for_collection_comp_with_acc","for_collection_proc_call","for_collection_rhs_capture","for_collection_if_and_local_var","for_collection_set","for_collection_list","for_sum_step","for_sum","while_sum","counter"]} |} ];
 
   run_ligo_good [ "list-declarations" ; "../../test/contracts/loop.mligo" ] ;
   [%expect {| {"source_file":"../../test/contracts/loop.mligo","declarations":["counter_nest","aux_nest","counter","counter_simple","aux_simple"]} |} ];

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

@@ -420,6 +420,8 @@ and for_int = {
   assign   : var_assign reg;
   kwd_to   : kwd_to;
   bound    : expr;
+  kwd_step : kwd_step option;
+  step     : expr option;
   block    : block reg
 }
 

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

@@ -105,6 +105,7 @@ type t =
 | Remove     of Region.t  (* "remove"     *)
 | Set        of Region.t  (* "set"        *)
 | Skip       of Region.t  (* "skip"       *)
+| Step       of Region.t  (* "step"       *)
 | Then       of Region.t  (* "then"       *)
 | To         of Region.t  (* "to"         *)
 | True       of Region.t  (* "True"       *)

src/passes/1-parser/pascaligo/LexToken.mll

@@ -103,6 +103,7 @@ type t =
 | Remove     of Region.t  (* "remove"     *)
 | Set        of Region.t  (* "set"        *)
 | Skip       of Region.t  (* "skip"       *)
+| Step       of Region.t  (* "step"       *)
 | Then       of Region.t  (* "then"       *)
 | To         of Region.t  (* "to"         *)
 | True       of Region.t  (* "True"       *)
@@ -216,6 +217,7 @@ let proj_token = function
 | Remove     region -> region, "Remove"
 | Set        region -> region, "Set"
 | Skip       region -> region, "Skip"
+| Step       region -> region, "Step"
 | Then       region -> region, "Then"
 | To         region -> region, "To"
 | True       region -> region, "True"
@@ -307,6 +309,7 @@ let to_lexeme = function
 | Remove     _ -> "remove"
 | Set        _ -> "set"
 | Skip       _ -> "skip"
+| Step       _ -> "step"
 | Then       _ -> "then"
 | To         _ -> "to"
 | True       _ -> "True"
@@ -368,6 +371,7 @@ let keywords = [
   (fun reg -> Remove     reg);
   (fun reg -> Set        reg);
   (fun reg -> Skip       reg);
+  (fun reg -> Step       reg);
   (fun reg -> Then       reg);
   (fun reg -> To         reg);
   (fun reg -> True       reg);
@@ -605,6 +609,7 @@ let is_kwd = function
 | Remove     _
 | Set        _
 | Skip       _
+| Step       _
 | Then       _
 | To         _
 | True       _

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

@@ -74,6 +74,7 @@
 %token <Region.t> Remove      "remove"
 %token <Region.t> Set         "set"
 %token <Region.t> Skip        "skip"
+%token <Region.t> Step        "step"
 %token <Region.t> Then        "then"
 %token <Region.t> To          "to"
 %token <Region.t> True        "True"

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

@@ -627,9 +627,22 @@ for_loop:
                   assign   = $2;
                   kwd_to   = $3;
                   bound    = $4;
+                  kwd_step = None;
+                  step     = None;
                   block    = $5}
     in For (ForInt {region; value})
   }
+| "for" var_assign "to" expr "step" expr block {
+    let region = cover $1 $7.region in
+    let value  = {kwd_for  = $1;
+                  assign   = $2;
+                  kwd_to   = $3;
+                  bound    = $4;
+                  kwd_step = Some $5;
+                  step     = Some $6;
+                  block    = $7}
+    in For (ForInt {region; value})
+  }
 | "for" var arrow_clause? "in" collection expr block {
     Scoping.check_reserved_name $2;
     let region = cover $1 $7.region in

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

@@ -392,11 +392,19 @@ and print_for_loop state = function
 | ForCollect for_collect -> print_for_collect state for_collect
 
 and print_for_int state ({value; _} : for_int reg) =
-  let {kwd_for; assign; kwd_to; bound; block} = value in
+  let {kwd_for; assign; kwd_to; bound; kwd_step; step; block} = value in
   print_token      state kwd_for "for";
   print_var_assign state assign;
   print_token      state kwd_to "to";
   print_expr       state bound;
+  match kwd_step with 
+  | None -> ();
+  | Some kwd_step -> 
+  print_token      state kwd_step "step";
+  match step with
+  | None -> ();
+  | Some step ->
+  print_expr       state step;
   print_block      state block
 
 and print_var_assign state {value; _} =

src/passes/2-concrete_to_imperative/pascaligo.ml

@@ -766,10 +766,12 @@ and compile_single_instruction : Raw.instruction -> (_ -> expression result) res
       let binder = Var.of_name fi.assign.value.name.value in
       let%bind start = compile_expression fi.assign.value.expr in
       let%bind bound = compile_expression fi.bound in
-      let increment = e_int 1 in
+      let%bind step = match fi.step with
+        | None -> ok @@ e_int 1 
+        | Some step -> compile_expression step in
       let%bind body = compile_block fi.block.value in
       let%bind body = body @@ None in
-      return_statement @@ e_for ~loc binder start bound increment body
+      return_statement @@ e_for ~loc binder start bound step body
   )
   | Loop (For (ForCollect fc)) ->
       let (fc,loc) = r_split fc in

src/test/contracts/loop.ligo

@@ -27,6 +27,15 @@ function for_sum (var n : nat) : int is
       }
   } with acc
 
+function for_sum_step (var n : nat) : int is
+  block {
+    var acc : int := 0;
+    for i := 1 to int (2n*n) step 2
+      block {
+        acc := acc + i
+      }
+  } with acc
+
 function for_collection_list (var nee : unit) : (int * string) is
   block {
     var acc : int := 0;

src/test/integration_tests.ml

@@ -1241,6 +1241,10 @@ let loop () : unit result =
     let make_input = e_nat in
     let make_expected = fun n -> e_int (n * (n + 1) / 2) in
     expect_eq_n_pos_mid program "for_sum" make_input make_expected in
+  let%bind () =
+    let make_input = e_nat in
+    let make_expected = fun n -> e_int (n * n) in
+    expect_eq_n_pos_mid program "for_sum_step" make_input make_expected in
   let input = e_unit () in
   let%bind () =
     let expected = e_pair (e_int 3) (e_string "totototo") in