modifying doc and test for loops (Cameligo and pascaligo)

gitlab-pages/docs/language-basics/loops.md

@@ -57,45 +57,21 @@ constant, therefore it makes no sense in CameLIGO to feature loops,
 which we understand as syntactic constructs where the state of a
 stopping condition is mutated, as with "while" loops in PascaLIGO.
 
-Instead, CameLIGO implements a *folded operation* by means of a
+Instead, CameLIGO loops are written by means of a tail recursive function
-predefined function named `Loop.fold_while`. It takes an initial value
-of a certain type, called an *accumulator*, and repeatedly calls a
-given function, called *folded function*, that takes that
-accumulator and returns the next value of the accumulator, until a
-condition is met and the fold stops with the final value of the
-accumulator. The iterated function needs to have a special type: if
-the type of the accumulator is `t`, then it must have the type `bool *
-t` (not simply `t`). It is the boolean value that denotes whether the
-stopping condition has been reached.
 
 Here is how to compute the greatest common divisors of two natural
 numbers by means of Euclid's algorithm:
 
 ```cameligo group=a
-let iter (x,y : nat * nat) : bool * (nat * nat) =
+let rec iter (x,y : nat * nat) : nat =
-  if y = 0n then false, (x,y) else true, (y, x mod y)
+  if y = 0n then x else iter (y, x mod y)
 
 let gcd (x,y : nat * nat) : nat =
   let x,y = if x < y then y,x else x,y in
-  let x,y = Loop.fold_while iter (x,y)
+  iter (x,y)
-  in x
 ```
 
-To ease the writing and reading of the iterated functions (here,
+> Note that `fold_while`, `stop` and `continue` (now `Loop.resume`) are
-`iter`), two predefined functions are provided: `Loop.resume` and
-`Loop.stop`:
-
-```cameligo group=a
-let iter (x,y : nat * nat) : bool * (nat * nat) =
-  if y = 0n then Loop.stop (x,y) else Loop.resume (y, x mod y)
-
-let gcd (x,y : nat * nat) : nat =
-  let x,y = if x < y then y,x else x,y in
-  let x,y = Loop.fold_while iter (x,y)
-  in x
-```
-
-> Note that `stop` and `continue` (now `Loop.resume`) are
 > *deprecated*.
 
 You can call the function `gcd` defined above using the LIGO compiler
@@ -114,47 +90,22 @@ constant, therefore it makes no sense in ReasonLIGO to feature loops,
 which we understand as syntactic constructs where the state of a
 stopping condition is mutated, as with "while" loops in PascaLIGO.
 
-Instead, ReasonLIGO features a *fold operation* as a predefined
+Instead, ReasonLIGO loops are written by means of tail recursive functions
-function named `Loop.fold_while`. It takes an initial value of a
-certain type, called an *accumulator*, and repeatedly calls a given
-function, called *iterated function*, that takes that accumulator and
-returns the next value of the accumulator, until a condition is met
-and the fold stops with the final value of the accumulator. The
-iterated function needs to have a special type: if the type of the
-accumulator is `t`, then it must have the type `bool * t` (not simply
-`t`). It is the boolean value that denotes whether the stopping
-condition has been reached.
 
 Here is how to compute the greatest common divisors of two natural
 numbers by means of Euclid's algorithm:
 
 ```reasonligo group=a
-let iter = ((x,y) : (nat, nat)) : (bool, (nat, nat)) =>
+let rec iter = ((x,y) : (nat, nat)) : nat =>
-  if (y == 0n) { (false, (x,y)); } else { (true, (y, x mod y)); };
+  if (y == 0n) { x; } else { iter ((y, x mod y)); };
 
 let gcd = ((x,y) : (nat, nat)) : nat => {
   let (x,y) = if (x < y) { (y,x); } else { (x,y); };
-  let (x,y) = Loop.fold_while (iter, (x,y));
+  iter ((x,y))
-  x
 };
 ```
 
-To ease the writing and reading of the iterated functions (here,
+> Note that `fold_while`, `stop` and `continue` (now `Loop.resume`) are
-`iter`), two predefined functions are provided: `Loop.resume` and
-`Loop.stop`:
-
-```reasonligo group=b
-let iter = ((x,y) : (nat, nat)) : (bool, (nat, nat)) =>
-  if (y == 0n) { Loop.stop ((x,y)); } else { Loop.resume ((y, x mod y)); };
-
-let gcd = ((x,y) : (nat, nat)) : nat => {
-  let (x,y) = if (x < y) { (y,x); } else { (x,y); };
-  let (x,y) = Loop.fold_while (iter, (x,y));
-  x
-};
-```
-
-> Note that `stop` and `continue` (now `Loop.resume`) are
 > *deprecated*.
 
 </Syntax>

src/bin/expect_tests/contract_tests.ml

@@ -1174,7 +1174,7 @@ 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 let rhs#810 = #P in let p = rhs#810.0 in let s = rhs#810.1 in ( list[] : (TO_list(operation)) , store ) , NONE() : (TO_option(key_hash)) , 300000000mutez , \"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 let rhs#808 = #P in let p = rhs#808.0 in let s = rhs#808.1 in ( list[] : (TO_list(operation)) , store ) , NONE() : (TO_option(key_hash)) , 300000000mutez , \"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
@@ -1187,7 +1187,7 @@ 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 let rhs#813 = #P in let p = rhs#813.0 in let s = rhs#813.1 in ( list[] : (TO_list(operation)) , a ) , NONE() : (TO_option(key_hash)) , 300000000mutez , 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 let rhs#811 = #P in let p = rhs#811.0 in let s = rhs#811.1 in ( list[] : (TO_list(operation)) , a ) , NONE() : (TO_option(key_hash)) , 300000000mutez , 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/passes/2-simplify/cameligo.ml

@@ -345,7 +345,7 @@ let rec simpl_expression :
   trace (simplifying_expr t) @@
   match t with
     Raw.ELetIn e ->
-      let Raw.{binding; body; attributes; _} = e.value in
+      let Raw.{kwd_rec; binding; body; attributes; _} = e.value in
       let inline = List.exists (fun (a: Raw.attribute) -> a.value = "inline") attributes in
       let Raw.{binders; lhs_type; let_rhs; _} = binding in
       begin match binders with
@@ -393,10 +393,50 @@ let rec simpl_expression :
           (chain_let_in tl body)
         | [] -> body (* Precluded by corner case assertion above *)
       in
-      if List.length prep_vars = 1
+      let%bind ty_opt = match ty_opt with 
-      then ok (chain_let_in prep_vars body)
+      | None -> (match let_rhs with 
-      (* Bind the right hand side so we only evaluate it once *)
+        | EFun {value={binders;lhs_type}} -> 
-      else ok (e_let_in (rhs_b, ty_opt) false inline rhs' (chain_let_in prep_vars body))
+          let f_args = nseq_to_list (binders) in
+          let%bind lhs_type' = bind_map_option (fun x -> simpl_type_expression (snd x)) lhs_type in
+          let%bind ty = bind_map_list typed_pattern_to_typed_vars f_args in
+          let aux acc ty = Option.map (t_function (snd ty)) acc in
+          ok @@ (List.fold_right' aux lhs_type' ty)
+        | _ -> ok None
+        )
+      | Some t -> ok @@ Some t
+      in
+      let%bind ret_expr = if List.length prep_vars = 1
+        then ok (chain_let_in prep_vars body)
+        (* Bind the right hand side so we only evaluate it once *)
+        else ok (e_let_in (rhs_b, ty_opt) false inline rhs' (chain_let_in prep_vars body))
+      in
+      let%bind ret_expr = match kwd_rec with 
+        | None -> ok @@ ret_expr
+        | Some _ -> 
+          match ret_expr.expression_content with 
+            | E_let_in li -> (
+              let%bind lambda = 
+                let rec aux rhs = match rhs.expression_content with
+                  | E_lambda l -> ok @@ l
+                  | E_ascription a -> aux a.anno_expr
+                  | _ -> fail @@ corner_case "recursive only supported for lambda"
+                in
+                aux rhs'
+              in
+              let fun_name = fst @@ List.hd prep_vars in
+              let%bind fun_type = match ty_opt with 
+                | Some t -> ok @@ t
+                | None -> match rhs'.expression_content with 
+                      | E_ascription a -> ok a.type_annotation
+                      | _ -> fail @@ untyped_recursive_function e
+              in
+              let expression_content = E_recursive {fun_name;fun_type;lambda} in
+              let expression_content = E_let_in {li with rhs = {li.rhs with  expression_content}} in
+              ok @@ {ret_expr with expression_content}
+          )
+          | _ -> fail @@ corner_case "impossible"
+      in
+      ok ret_expr
 
       (* let f p1 ps... = rhs in body *)
       | (f, p1 :: ps) ->
@@ -670,7 +710,8 @@ and simpl_fun lamb' : expr result =
       e_lambda ~loc (binder) (Some input_type) output_type (layer_arguments tl)
     | [] -> body
   in
-  return @@ layer_arguments params'
+  let ret_lamb = layer_arguments params' in
+  return @@ ret_lamb
 
 
 and simpl_logic_expression ?te_annot (t:Raw.logic_expr) : expr result =

src/passes/2-simplify/pascaligo.ml

@@ -1263,11 +1263,12 @@ and simpl_for_int : Raw.for_int -> (_ -> expression result) result = fun fi ->
   let%bind bound = simpl_expression fi.bound in
   let cond = e_annotation (e_constant C_LE [var ; bound]) t_bool in
   let step = e_int 1 in
+  let continue_expr = e_constant C_FOLD_CONTINUE [(e_variable binder)] in
   let ctrl = 
-    e_let_in (it,Some t_int) false false (e_constant C_ADD [ var ; step ]) 
+    e_let_in (it,Some t_int) false false (e_constant C_ADD [ var ; step ]) @@
-    (e_let_in (binder, None) false false (e_update (e_variable binder) "1" var)
+    e_let_in (binder, None) false false (e_update (e_variable binder) "1" var)@@
-    (e_variable binder))
+    continue_expr
-    in
+  in
   (* Modify the body loop*)
   let%bind for_body = simpl_block fi.block.value in
   let%bind for_body = for_body @@ Some ctrl in
@@ -1281,11 +1282,10 @@ and simpl_for_int : Raw.for_int -> (_ -> expression result) result = fun fi ->
   let restore = fun expr -> List.fold_right aux captured_name_list expr in
 
   (*Prep the lambda for the fold*)
-  let continue_expr = e_constant C_FOLD_CONTINUE [restore(for_body)] in
   let stop_expr = e_constant C_FOLD_STOP [e_variable binder] in
   let aux_func = e_lambda binder None None @@ 
                  e_let_in (it,Some t_int) false false (e_accessor (e_variable binder) "1") @@
-                 e_cond cond continue_expr (stop_expr) in
+                 e_cond cond (restore for_body) (stop_expr) in
 
   (* Make the fold_while en precharge the vakye *)
   let loop = e_constant C_FOLD_WHILE [aux_func; e_variable env_rec] in

src/passes/6-transpiler/transpiler.ml

@@ -101,6 +101,15 @@ them. please report this to the developers." in
       ("value" , fun () -> Format.asprintf "%a" Mini_c.PP.value value) ;
     ] in
     error ~data title content
+  
+  let unsupported_recursive_function expression_variable =
+    let title () = "unsupported recursive function yet" in
+    let content () = "only fuction with one variable are supported" in
+    let data = [
+      ("value" , fun () -> Format.asprintf "%a" AST.PP.expression_variable expression_variable) ;
+    ] in
+    error ~data title content
+
 
 end
 open Errors
@@ -521,12 +530,14 @@ and transpile_lambda l (input_type , output_type) =
   ok @@ Combinators.Expression.make_tpl (closure , tv)
 
 and transpile_recursive {fun_name; fun_type; lambda} =
-  let rec map_lambda : AST.expression_variable -> type_value -> AST.expression -> expression result = fun fun_name loop_type e ->
+  let rec map_lambda : AST.expression_variable -> type_value -> AST.expression -> (expression * expression_variable list) result = fun fun_name loop_type e ->
     match e.expression_content with 
       E_lambda {binder;result} -> 
-        let%bind body = map_lambda fun_name loop_type result in
+        let%bind (body,l) = map_lambda fun_name loop_type result in
-        ok @@ Expression.make (E_closure {binder;body}) loop_type|
+        ok @@ (Expression.make (E_closure {binder;body}) loop_type, binder::l)
-      _  -> replace_callback fun_name loop_type e
+      | _  -> 
+        let%bind res = replace_callback fun_name loop_type e in
+        ok @@ (res, [])
 
   and replace_callback : AST.expression_variable -> type_value -> AST.expression -> expression result = fun fun_name loop_type e ->
     match e.expression_content with
@@ -629,10 +640,13 @@ and transpile_recursive {fun_name; fun_type; lambda} =
   let%bind fun_type = transpile_type fun_type in
   let%bind (input_type,output_type) = get_t_function fun_type in
   let loop_type = t_union (None, input_type) (None, output_type) in
-  let%bind body = map_lambda fun_name loop_type lambda.result in
+  let%bind (body,binder) = map_lambda fun_name loop_type lambda.result in
-  let expr = Expression.make_tpl (E_variable fun_name, input_type) in
+  let binder = lambda.binder::binder in
+  List.iter (Format.printf "inder %a\n%!" Var.pp) binder ;
+  let%bind binder = match binder with hd::[] -> ok @@ hd | _ -> fail @@ unsupported_recursive_function fun_name in
+  let expr = Expression.make_tpl (E_variable binder, input_type) in
   let body = Expression.make (E_iterator (C_LOOP_LEFT, ((lambda.binder, loop_type),body), expr)) output_type in
-  ok @@ Expression.make (E_closure {binder=fun_name;body}) fun_type
+  ok @@ Expression.make (E_closure {binder;body}) fun_type
 
 let transpile_declaration env (d:AST.declaration) : toplevel_statement result =
   match d with

src/stages/ast_typed/combinators.ml

@@ -168,6 +168,17 @@ let get_t_function (t:type_expression) : (type_expression * type_expression) res
   | T_arrow {type1;type2} -> ok (type1,type2)
   | _ -> simple_fail "not a function"
 
+let get_t_function_full (t:type_expression) : (type_expression * type_expression) result =
+  let%bind _ = get_t_function t in
+  let rec aux n t = match t.type_content with 
+    | T_arrow {type1;type2} -> 
+      let (l, o) = aux (n+1) type2 in
+      ((Label (string_of_int n),type1)::l,o)
+    | _ -> ([],t)
+  in
+  let (input,output) = aux 0 t in
+  ok @@ (t_record (LMap.of_list input) (),output) 
+
 let get_t_sum (t:type_expression) : type_expression constructor_map result = match t.type_content with
   | T_sum m -> ok m
   | _ -> fail @@ Errors.not_a_x_type "sum" t ()

src/stages/ast_typed/combinators.mli

@@ -62,6 +62,7 @@ val get_t_key_hash : type_expression -> unit result
 val get_t_tuple : type_expression -> type_expression list result
 val get_t_pair : type_expression -> ( type_expression * type_expression ) result
 val get_t_function : type_expression -> ( type_expression * type_expression ) result
+val get_t_function_full : type_expression -> ( type_expression * type_expression ) result
 val get_t_sum : type_expression -> type_expression constructor_map result
 val get_t_record : type_expression -> type_expression label_map result
 val get_t_map : type_expression -> ( type_expression * type_expression ) result

src/test/contracts/loop.mligo

@@ -1,10 +1,9 @@
 (* Test functional iterators in CameLIGO *)
 
-let aux_simple (i : int) : bool * int =
+let rec aux_simple (i : int) : int =
-  if i < 100 then Loop.resume (i + 1) else Loop.stop i
+  if i < 100 then aux_simple (i + 1) else i
 
-let counter_simple (n : int) : int =
+let counter_simple (n : int) : int = aux_simple n
-  Loop.fold_while aux_simple n
 
 type sum_aggregator = {
   counter : int;
@@ -13,25 +12,23 @@ type sum_aggregator = {
 
 let counter (n : int) : int =
   let initial : sum_aggregator = {counter=0; sum=0} in
-  let aggregate = fun (prev : sum_aggregator) ->
+  let rec aggregate : sum_aggregator -> int = fun (prev: sum_aggregator) ->
     if prev.counter <= n then
-      Loop.resume {counter = prev.counter + 1;
+      aggregate {counter = prev.counter + 1;
                    sum = prev.counter + prev.sum}
     else
-      Loop.stop {counter = prev.counter; sum = prev.sum} in
+      prev.sum 
-  let out : sum_aggregator =
+  in
-    Loop.fold_while aggregate initial
+  aggregate initial
-  in out.sum
 
-let aux_nest (prev : sum_aggregator) : bool * sum_aggregator =
+let rec aux_nest (prev : sum_aggregator) : int =
   if prev.counter < 100 then
-    let sum : int =
+    let sum = prev.sum + (aux_simple prev.counter) in
-      prev.sum + Loop.fold_while aux_simple prev.counter
+    aux_nest {counter = prev.counter + 1; sum = sum}
-    in Loop.resume {counter = prev.counter + 1; sum = sum}
   else
-    Loop.stop {counter = prev.counter; sum = prev.sum}
+    prev.sum
 
 let counter_nest (n : int) : int =
   let initial : sum_aggregator = {counter=0; sum=0} in
-  let out : sum_aggregator = Loop.fold_while aux_nest initial
+  let out = aux_nest initial
-  in out.sum
+  in out

src/test/contracts/loop.religo

@@ -1,9 +1,9 @@
 /* Test loops in ReasonLIGO */
 
-let aux_simple = (i : int) : (bool, int) =>
+let rec aux_simple = (i : int) : int =>
-  if (i < 100) { Loop.resume (i + 1); } else { Loop.stop (i); };
+  if (i < 100) { aux_simple (i + 1); } else { i; };
 
-let counter_simple = (n : int) : int => Loop.fold_while (aux_simple, n);
+let counter_simple = (n : int) : int => aux_simple (n);
 
 type sum_aggregator = {
   counter : int,
@@ -12,30 +12,28 @@ type sum_aggregator = {
 
 let counter = (n : int) : int => {
   let initial : sum_aggregator = {counter: 0, sum: 0};
-  let aggregate = (prev : sum_aggregator) =>
+  let rec aggregate = (prev : sum_aggregator):int =>
     if (prev.counter <= n) {
-      Loop.resume ({counter : prev.counter + 1,
+      aggregate ({counter : prev.counter + 1,
                     sum : prev.counter + prev.sum});
     } else {
-      Loop.stop ({counter: prev.counter, sum: prev.sum});
+      prev.sum;
     };
-  let out : sum_aggregator =
+  aggregate (initial);
-    Loop.fold_while (aggregate, initial);
-  out.sum;
 };
 
-let aux_nest = (prev : sum_aggregator) : (bool, sum_aggregator) =>
+let rec aux_nest = (prev : sum_aggregator) : sum_aggregator =>
   if (prev.counter < 100) {
     let sum : int =
-      prev.sum + Loop.fold_while (aux_simple, prev.counter);
+      prev.sum + aux_simple (prev.counter);
-    Loop.resume ({counter: prev.counter + 1,
+    aux_nest ({counter: prev.counter + 1,
                   sum: sum});
   } else {
-    Loop.stop ({counter: prev.counter, sum: prev.sum});
+    ({counter: prev.counter, sum: prev.sum});
   };
 
 let counter_nest = (n : int) : int => {
   let initial : sum_aggregator = {counter: 0, sum: 0};
-  let out : sum_aggregator = Loop.fold_while (aux_nest, initial);
+  let out : sum_aggregator = aux_nest (initial);
   out.sum;
 };