diff --git a/lib/02_parsing/Parser.ml b/lib/02_parsing/Parser.ml
index df238c0..ab230f5 100644
--- a/lib/02_parsing/Parser.ml
+++ b/lib/02_parsing/Parser.ml
@@ -248,16 +248,11 @@ module Rules = struct
     let start_token = t.token in
     let attributes =
       if t |> optional Token.LEFT_PAREN then (
-        let res =
-          t
-          |> Helpers.separated_list ~fn:parse_attribute ~sep:Token.COMMA
-          |> List.to_seq
-          |> StringMap.of_seq
-        in
+        let res = t |> Helpers.separated_list ~fn:parse_attribute ~sep:Token.COMMA in
         t |> expect Token.RIGHT_PAREN;
         res)
       else
-        StringMap.empty
+        []
     in
     let transformer =
       let start_token = t.token in
@@ -334,10 +329,7 @@ module Rules = struct
       | Token.HTML_OPEN_TAG html_tag_identifier ->
           next t;
           let html_tag_attributes =
-            t
-            |> Helpers.list ~fn:(parse_attribute ~sep:Token.EQUAL)
-            |> List.to_seq
-            |> StringMap.of_seq
+            t |> Helpers.list ~fn:(parse_attribute ~sep:Token.EQUAL)
           in
           let html_tag_self_closing =
             t |> optional Token.HTML_OR_COMPONENT_TAG_SELF_CLOSING
@@ -370,10 +362,7 @@ module Rules = struct
           in
           next t;
           let component_tag_attributes =
-            t
-            |> Helpers.list ~fn:(parse_attribute ~sep:Token.EQUAL)
-            |> List.to_seq
-            |> StringMap.of_seq
+            t |> Helpers.list ~fn:(parse_attribute ~sep:Token.EQUAL)
           in
           let component_tag_self_closing =
             t |> optional Token.HTML_OR_COMPONENT_TAG_SELF_CLOSING
@@ -554,10 +543,7 @@ module Rules = struct
           if is_record then (
             next t;
             let attrs =
-              t
-              |> Helpers.separated_list ~sep:Token.COMMA ~fn:parse_record_field
-              |> List.to_seq
-              |> StringMap.of_seq
+              t |> Helpers.separated_list ~sep:Token.COMMA ~fn:parse_record_field
             in
             t |> expect Token.RIGHT_BRACE;
             let end_location = t.token.location in
@@ -718,7 +704,6 @@ module Rules = struct
           next t;
           let expressions =
             Helpers.separated_list ~sep:Token.COMMA ~fn:parse_expression t
-            |> Array.of_list
           in
           let end_location = t.token.location in
           expect Token.RIGHT_BRACK t;
@@ -819,13 +804,11 @@ module Rules = struct
             if optional Token.LEFT_PAREN t then (
               let attributes =
                 Helpers.separated_list ~sep:Token.COMMA ~fn:parse_attribute t
-                |> List.to_seq
-                |> StringMap.of_seq
               in
               t |> expect Token.RIGHT_PAREN;
               attributes)
             else
-              StringMap.empty
+              []
           in
           let declaration_body = t |> parse_expression in
           match declaration_body with
@@ -878,11 +861,11 @@ let parse ?(include_stdlib = true) sources : Parsetree.t =
       []
   in
   stdlib @ sources
-  |> ListLabels.fold_left ~init:StringMap.empty ~f:(fun acc source ->
+  |> ListLabels.fold_left ~init:[] ~f:(fun acc source ->
       let decls = parse_source source in
       ListLabels.fold_left decls ~init:acc ~f:(fun acc (key, decl) ->
-          match StringMap.find_opt key acc with
-          | None -> StringMap.add key decl acc
+          match List.assoc_opt key acc with
+          | None -> (key, decl) :: acc
           | Some _ ->
               let message =
                 Printf.sprintf
@@ -892,4 +875,5 @@ let parse ?(include_stdlib = true) sources : Parsetree.t =
               in
 
               Pinc_Diagnostics.raise_error decl.Parsetree.declaration_loc message))
+  |> List.rev
 ;;
diff --git a/lib/02_parsing/Parsetree.ml b/lib/02_parsing/Parsetree.ml
index d13cd53..706fab6 100644
--- a/lib/02_parsing/Parsetree.ml
+++ b/lib/02_parsing/Parsetree.ml
@@ -9,13 +9,13 @@ and template_node = {
 and template_node_desc =
   | P_HtmlTemplateNode of {
       html_tag_identifier : string;
-      html_tag_attributes : expression StringMap.t;
+      html_tag_attributes : (string * expression) list;
       html_tag_children : template_node list;
       html_tag_self_closing : bool;
     }
   | P_ComponentTemplateNode of {
       component_tag_identifier : uppercase_identifier;
-      component_tag_attributes : expression StringMap.t;
+      component_tag_attributes : (string * expression) list;
       component_tag_children : template_node list;
     }
   | P_FragmentTemplateNode of { fragement_children : template_node list }
@@ -44,7 +44,7 @@ and tag_kind =
 
 and tag_desc = {
   tag : tag_kind;
-  attributes : expression StringMap.t;
+  attributes : (string * expression) list;
   transformer : expression option;
 }
 
@@ -69,8 +69,8 @@ and expression_desc =
   | P_Int of int
   | P_Float of float
   | P_Bool of bool
-  | P_Array of expression array
-  | P_Record of ([ `Required | `Optional ] * expression) StringMap.t
+  | P_Array of expression list
+  | P_Record of (string * ([ `Required | `Optional ] * expression)) list
   | P_ExternalFunction of {
       parameters : lowercase_identifier list;
       name : string;
@@ -133,11 +133,11 @@ and declaration_kind =
   | P_Declaration_Store of declaration_desc
 
 and declaration_desc = {
-  declaration_attributes : expression StringMap.t;
+  declaration_attributes : (string * expression) list;
   declaration_body : expression;
 }
 
-and t = declaration StringMap.t
+and t = (string * declaration) list
 
 module Declaration = struct
   let marshal (d : declaration) = Marshal.to_string d []
diff --git a/lib/02_parsing/Transformer.ml b/lib/02_parsing/Transformer.ml
index bb1a3c5..f6ade42 100644
--- a/lib/02_parsing/Transformer.ml
+++ b/lib/02_parsing/Transformer.ml
@@ -66,12 +66,14 @@ and transform_float env f = (env, Float f)
 and transform_bool env b = (env, Bool b)
 
 and transform_array env a =
-  let env, array = Array.fold_map ~init:env ~f:transform_expression a in
-  (env, Array array)
+  let env, array = List.fold_map ~init:env ~f:transform_expression a in
+  (env, Array (Array.of_list array))
 
 and transform_record env r =
   let env, r =
-    StringMap.fold_mapi r ~init:env ~f:(fun key env (requirement, expr) ->
+    r
+    |> StringMap.of_list
+    |> StringMap.fold_mapi ~init:env ~f:(fun key env (requirement, expr) ->
         let env =
           {
             env with
@@ -127,6 +129,7 @@ and transform_tag env (tag : Parsetree.tag) =
     let current_identifier = env.Env.current_identifier in
     let child_env, children =
       desc.attributes
+      |> StringMap.of_list
       |> StringMap.find_opt "of"
       |> Option.fold_map
            ~init:
@@ -144,6 +147,7 @@ and transform_tag env (tag : Parsetree.tag) =
     in
     let env, attributes =
       desc.attributes
+      |> StringMap.of_list
       |> StringMap.remove "of"
       |> StringMap.fold_map ~init:env ~f:transform_expression
     in
@@ -371,7 +375,9 @@ and transform_html_template_node
     ~html_tag_self_closing =
   let html_tag_identifier = html_tag_identifier in
   let env, html_tag_attributes =
-    StringMap.fold_map ~init:env ~f:transform_expression html_tag_attributes
+    html_tag_attributes
+    |> StringMap.of_list
+    |> StringMap.fold_map ~init:env ~f:transform_expression
   in
   let env, html_tag_children =
     List.fold_map ~init:env ~f:transform_template_node html_tag_children
@@ -401,7 +407,9 @@ and transform_component_template_node
     transform_uppercase_id env component_tag_identifier
   in
   let env, component_tag_attributes =
-    StringMap.fold_map ~init:env ~f:transform_expression component_tag_attributes
+    component_tag_attributes
+    |> StringMap.of_list
+    |> StringMap.fold_map ~init:env ~f:transform_expression
   in
   let env, component_tag_children =
     List.fold_map ~init:env ~f:transform_template_node component_tag_children
@@ -553,40 +561,36 @@ and transform_statement env (statement : Parsetree.statement) =
 
 and transform_component_declaration env (declaration : Parsetree.declaration_desc) =
   let env, declaration_attributes =
-    StringMap.fold_map
-      ~init:env
-      ~f:transform_expression
-      declaration.declaration_attributes
+    declaration.declaration_attributes
+    |> StringMap.of_list
+    |> StringMap.fold_map ~init:env ~f:transform_expression
   in
   let env, declaration_body = transform_expression env declaration.declaration_body in
   (env, Declaration_Component { declaration_attributes; declaration_body })
 
 and transform_library_declaration env (declaration : Parsetree.declaration_desc) =
   let env, declaration_attributes =
-    StringMap.fold_map
-      ~init:env
-      ~f:transform_expression
-      declaration.declaration_attributes
+    declaration.declaration_attributes
+    |> StringMap.of_list
+    |> StringMap.fold_map ~init:env ~f:transform_expression
   in
   let env, declaration_body = transform_expression env declaration.declaration_body in
   (env, Declaration_Library { declaration_attributes; declaration_body })
 
 and transform_page_declaration env (declaration : Parsetree.declaration_desc) =
   let env, declaration_attributes =
-    StringMap.fold_map
-      ~init:env
-      ~f:transform_expression
-      declaration.declaration_attributes
+    declaration.declaration_attributes
+    |> StringMap.of_list
+    |> StringMap.fold_map ~init:env ~f:transform_expression
   in
   let env, declaration_body = transform_expression env declaration.declaration_body in
   (env, Declaration_Page { declaration_attributes; declaration_body })
 
 and transform_store_declaration env (declaration : Parsetree.declaration_desc) =
   let env, declaration_attributes =
-    StringMap.fold_map
-      ~init:env
-      ~f:transform_expression
-      declaration.declaration_attributes
+    declaration.declaration_attributes
+    |> StringMap.of_list
+    |> StringMap.fold_map ~init:env ~f:transform_expression
   in
   let env, declaration_body = transform_expression env declaration.declaration_body in
   (env, Declaration_Store { declaration_attributes; declaration_body })
@@ -602,7 +606,9 @@ and transform_declaration env (declaration : Parsetree.declaration) =
   (env, { declaration_loc = declaration.declaration_loc; declaration_kind })
 
 and transform_declarations env declarations =
-  StringMap.fold_map ~init:env ~f:transform_declaration declarations
+  declarations
+  |> StringMap.of_list
+  |> StringMap.fold_map ~init:env ~f:transform_declaration
 ;;
 
 let transform (declarations : Parsetree.t) : Ast.t =
@@ -613,7 +619,7 @@ let transform (declarations : Parsetree.t) : Ast.t =
 
 let all_tags key declarations =
   let env = Env.empty in
-  let declaration = StringMap.find_opt key declarations in
+  let declaration = List.assoc_opt key declarations in
   match declaration with
   | None -> env.tags
   | Some declaration ->