redo rowfold, iter, and map

src/letsqlite.ml

@@ -57,13 +57,33 @@ let reset (v,s) = lift_err (S.reset s) (v,s)
 let step (v,s) = lift_err (S.step s) (v,s)
 let bind_values l (v,s) = lift_err (S.bind_values s l) (v,s)
 let clear_bindings (v,s) = lift_err (S.clear_bindings s) (v,s)
-let rowfold f (v,s) =
-	let g x arr = f x (create_rowtbl s arr)
-	in let (r,x) = S.fold ~f:g ~init:v s
-	in if Rc.is_success r then Norm (x,s)
-	else stmtfail r s
-let rowfold_init f i = inject i @>$ rowfold f
-let iter f = rowfold_init (fun () x -> f x) ()
+
+let execif r v = if Rc.is_success r then Norm v else Failed r
+
+let rowfold f (init,s) =
+	let rec fold acc ((),s) =
+		let r = S.step s
+		in if r = Rc.ROW then
+		match f acc (create_rowtbl s (S.row_data s)) with
+			| Error r -> stmtfail r s
+			| Ok x -> fold x ((),s)
+		else execif r (acc,s)
+	in fold init ((),s) >>$ reset
+
+let iter f (_,s) =
+	let wrap () x = let r = f x in
+		if r = Rc.OK then Ok ()
+		else Error r
+	in rowfold wrap ((),s)
+
+let map f l (ival,s) =
+	let rec map l (b,s) = match l with
+	| [] -> Norm (b,s)
+	| h::t ->
+		let$ v,s = f h (ival,s)
+		in map t (v::b,s)
+	in let$ (v,s) = map l ([],s)
+	in Norm (List.rev v, s)
 
 let rec fold f l (v,s) = match l with
 | [] -> Norm (v,s)

src/letsqlite.mli

@@ -106,17 +106,18 @@ val step : ('a,'a) monad_fun
     {b NOTE}: [step] will fail when the statement returns a row.
 *)
 
-val rowfold : ('a -> rowdata -> 'a) -> ('a,'a) monad_fun
+val rowfold : ('a -> rowdata -> ('a,Sqlite3.Rc.t) Result.t) -> ('a,'a) monad_fun
 (** [rowfold f] iterates over each row returns by [S] and applies
     [f] to it, returning some value. *)
 
-val rowfold_init : ('a -> rowdata -> 'a) -> 'a -> ('b,'a) monad_fun
-(** [rowfold_initf i] changes [V] to [i] and then applies [rowfold]. *)
-
-val iter : (rowdata -> unit) -> ('a,unit) monad_fun
+val iter : (rowdata -> Sqlite3.Rc.t) -> ('a,unit) monad_fun
 (** [rowfold_unit f] is equivalent to [rowfold_init f ()] but [f]
     is not passed a unit argument. *)
 
+val map : ('a -> ('b,'c) monad_fun) -> 'a list -> ('b,'c list) monad_fun
+(** [map f l] applies the monadic function [f] to each element of [l],
+    returning all the list of all their values. *)
+
 val fold : ('a -> ('b,'b) monad_fun) -> 'a list -> ('b,'b) monad_fun
 (** [fold f l] applies each element of [l] to make a monadic function [f]. *)