Rename std to syntax and add more list functions in Result

src/dune

@@ -30,7 +30,7 @@
   solver
   solver_intf
   solver_dispatcher
-  std
+  syntax
   symbol
   statistics
   ty

src/stdlib/syntax.ml

@@ -0,0 +1,47 @@
+module Option = struct
+  include Option
+
+  let ( let* ) v f = bind v f
+
+  let ( let+ ) v f = map f v
+end
+
+module Result = struct
+  include Result
+
+  let ( let* ) v f = Result.bind v f
+
+  let ( let+ ) v f = Result.map f v
+
+  let rec list_iter f = function
+    | [] -> Ok ()
+    | hd :: tl ->
+      let* () = f hd in
+      list_iter f tl
+
+  let list_map f v =
+    let rec list_map_cps f v k =
+      match v with
+      | [] -> k (Ok [])
+      | hd :: tl ->
+        list_map_cps f tl (fun rest ->
+            let* rest in
+            let* hd' = f hd in
+            k (Ok (hd' :: rest)) )
+    in
+    list_map_cps f v Fun.id
+
+  let list_filter_map f v =
+    let rec list_filter_map_cps f v k =
+      match v with
+      | [] -> k (Ok [])
+      | hd :: tl ->
+        list_filter_map_cps f tl (fun rest ->
+            let* rest in
+            match f hd with
+            | Error _ as e -> k e
+            | Ok None -> k (Ok rest)
+            | Ok (Some v) -> k (Ok (v :: rest)) )
+    in
+    list_filter_map_cps f v Fun.id
+end