diff --git a/src/super_context.ml b/src/super_context.ml
index bb228365..6c59e708 100644
--- a/src/super_context.ml
+++ b/src/super_context.ml
@@ -33,243 +33,6 @@ module Env_node = struct
     }
 end
 
-module Var : sig
-  module Kind : sig
-    type t =
-      | Values of Value.t list
-      | Project_root
-      | First_dep
-      | Deps
-      | Targets
-
-    val to_value_no_deps_or_targets : t -> scope:Scope.t -> Value.t list option
-  end
-
-  module Form : sig
-    type t =
-      | Exe
-      | Dep
-      | Bin
-      | Lib
-      | Libexec
-      | Lib_available
-      | Version
-      | Read
-      | Read_strings
-      | Read_lines
-      | Path_no_dep
-  end
-
-  type 'a t =
-    | No_info    of 'a
-    | Since      of 'a * Syntax.Version.t
-    | Deleted_in of 'a * Syntax.Version.t
-    | Renamed_in of Syntax.Version.t * string
-
-  module Map : sig
-    type 'a var
-    type 'a t
-
-    val create_vars : context:Context.t -> cxx_flags:string list -> Kind.t t
-
-    val forms : Form.t t
-
-    val static_vars : Kind.t t
-
-    val expand
-      :  'a t
-      -> syntax_version:Syntax.Version.t
-      -> var:String_with_vars.Var.t
-      -> 'a option
-  end with type 'a var := 'a t
-end = struct
-  module Kind = struct
-    type t =
-      | Values of Value.t list
-      | Project_root
-      | First_dep
-      | Deps
-      | Targets
-
-    let to_value_no_deps_or_targets t ~scope =
-      match t with
-      | Values v -> Some v
-      | Project_root -> Some [Value.Dir (Scope.root scope)]
-      | First_dep
-      | Deps
-      | Targets -> None
-  end
-
-  module Form = struct
-    type t =
-      | Exe
-      | Dep
-      | Bin
-      | Lib
-      | Libexec
-      | Lib_available
-      | Version
-      | Read
-      | Read_strings
-      | Read_lines
-      | Path_no_dep
-  end
-
-  type 'a t =
-    | No_info    of 'a
-    | Since      of 'a * Syntax.Version.t
-    | Deleted_in of 'a * Syntax.Version.t
-    | Renamed_in of Syntax.Version.t * string
-
-  module Map = struct
-    type nonrec 'a t = 'a t String.Map.t
-
-    let values v                      = No_info (Kind.Values v)
-    let renamed_in ~new_name ~version = Renamed_in (version, new_name)
-    let deleted_in ~version kind      = Deleted_in (kind, version)
-    let since ~version v              = Since (v, version)
-
-    let static_vars =
-      [ "first-dep", since ~version:(1, 0) Kind.First_dep
-      ; "targets", since ~version:(1, 0) Kind.Targets
-      ; "deps", since ~version:(1, 0) Kind.Deps
-      ; "project_root", since ~version:(1, 0) Kind.Project_root
-
-      ; "<", renamed_in ~version:(1, 0) ~new_name:"first-dep"
-      ; "@", renamed_in ~version:(1, 0) ~new_name:"targets"
-      ; "^", renamed_in ~version:(1, 0) ~new_name:"deps"
-      ; "SCOPE_ROOT", renamed_in ~version:(1, 0) ~new_name:"project_root"
-      ]
-
-    let forms =
-      let form kind = No_info kind in
-      let open Form in
-      [ "exe", form Exe
-      ; "bin", form Bin
-      ; "lib", form Lib
-      ; "libexec", form Libexec
-      ; "lib-available", form Lib_available
-      ; "version", form Version
-      ; "read", form Read
-      ; "read-lines", form Read_lines
-      ; "read-strings", form Read_strings
-
-      ; "dep", since ~version:(1, 0) Dep
-
-      ; "path", renamed_in ~version:(1, 0) ~new_name:"dep"
-      ; "findlib", renamed_in ~version:(1, 0) ~new_name:"lib"
-
-      ; "path-no-dep", deleted_in ~version:(1, 0) Path_no_dep
-      ]
-      |> String.Map.of_list_exn
-
-    let create_vars ~(context : Context.t) ~cxx_flags =
-      let ocamlopt =
-        match context.ocamlopt with
-        | None -> Path.relative context.ocaml_bin "ocamlopt"
-        | Some p -> p
-      in
-      let string s = values [Value.String s] in
-      let path p = values [Value.Path p] in
-      let make =
-        match Bin.make with
-        | None   -> string "make"
-        | Some p -> path p
-      in
-      let cflags = context.ocamlc_cflags in
-      let strings s = values (Value.L.strings s) in
-      let lowercased =
-        [ "cpp"            , strings (context.c_compiler :: cflags @ ["-E"])
-        ; "cc"             , strings (context.c_compiler :: cflags)
-        ; "cxx"            , strings (context.c_compiler :: cxx_flags)
-        ; "ocaml"          , path context.ocaml
-        ; "ocamlc"         , path context.ocamlc
-        ; "ocamlopt"       , path ocamlopt
-        ; "arch_sixtyfour" , string (string_of_bool context.arch_sixtyfour)
-        ; "make"           , make
-        ; "root"           , values [Value.Dir context.build_dir]
-        ] in
-      let uppercased =
-        List.map lowercased ~f:(fun (k, _) ->
-          (String.uppercase k, renamed_in ~new_name:k ~version:(1, 0))) in
-      let vars =
-        [ "-verbose"       , values []
-        ; "pa_cpp"         , strings (context.c_compiler :: cflags
-                                      @ ["-undef"; "-traditional";
-                                         "-x"; "c"; "-E"])
-        ; "ocaml_bin"      , path context.ocaml_bin
-        ; "ocaml_version"  , string context.version_string
-        ; "ocaml_where"    , string (Path.to_string context.stdlib_dir)
-        ; "null"           , string (Path.to_string Config.dev_null)
-        ; "ext_obj"        , string context.ext_obj
-        ; "ext_asm"        , string context.ext_asm
-        ; "ext_lib"        , string context.ext_lib
-        ; "ext_dll"        , string context.ext_dll
-        ; "ext_exe"        , string context.ext_exe
-        ; "profile"        , string context.profile
-        ]
-      in
-      let ocaml_config =
-        List.map (Ocaml_config.to_list context.ocaml_config) ~f:(fun (k, v) ->
-          ("ocaml-config:" ^ k,
-           match (v : Ocaml_config.Value.t) with
-           | Bool   x -> string (string_of_bool x)
-           | Int    x -> string (string_of_int x)
-           | String x -> string x
-           | Words  x -> strings x
-           | Prog_and_args x -> strings (x.prog :: x.args)))
-      in
-      [ ocaml_config
-      ; static_vars
-      ; lowercased
-      ; uppercased
-      ; vars
-      ]
-      |> List.concat
-      |> String.Map.of_list_exn
-
-    let static_vars = String.Map.of_list_exn static_vars
-
-    let rec expand t ~syntax_version ~var =
-      let name = String_with_vars.Var.name var in
-      Option.bind (String.Map.find t name) ~f:(fun v ->
-        let what var =
-          sprintf "Variable %s" (String_with_vars.Var.to_string var) in
-        match v with
-        | No_info v -> Some v
-        | Since (v, min_version) ->
-          if syntax_version >= min_version then
-            Some v
-          else
-            Syntax.Error.since (String_with_vars.Var.loc var)
-              Stanza.syntax syntax_version
-              ~what:(what var)
-        | Renamed_in (in_version, new_name) -> begin
-            if syntax_version >= in_version then
-              let var =
-                if String_with_vars.Var.is_form var then
-                  String_with_vars.Var.with_payload var ~payload:(Some "..")
-                else
-                  var
-              in
-              Syntax.Error.renamed_in (String_with_vars.Var.loc var)
-                Stanza.syntax syntax_version
-                ~what:(what var)
-                ~to_:(let open String_with_vars.Var in
-                  to_string (with_name var ~name:new_name))
-            else
-              expand t ~syntax_version:in_version
-                ~var:(String_with_vars.Var.with_name var ~name:new_name)
-          end
-        | Deleted_in (v, in_version) ->
-          if syntax_version < in_version then
-            Some v
-          else
-            Syntax.Error.deleted_in (String_with_vars.Var.loc var)
-              Stanza.syntax syntax_version ~what:(what var))
-  end
-end
-
 type t =
   { context                          : Context.t
   ; build_system                     : Build_system.t
diff --git a/src/var.ml b/src/var.ml
new file mode 100644
index 00000000..7713a6a1
--- /dev/null
+++ b/src/var.ml
@@ -0,0 +1,187 @@
+open Import
+
+module Kind = struct
+  type t =
+    | Values of Value.t list
+    | Project_root
+    | First_dep
+    | Deps
+    | Targets
+
+  let to_value_no_deps_or_targets t ~scope =
+    match t with
+    | Values v -> Some v
+    | Project_root -> Some [Value.Dir (Scope.root scope)]
+    | First_dep
+    | Deps
+    | Targets -> None
+end
+
+module Form = struct
+  type t =
+    | Exe
+    | Dep
+    | Bin
+    | Lib
+    | Libexec
+    | Lib_available
+    | Version
+    | Read
+    | Read_strings
+    | Read_lines
+    | Path_no_dep
+end
+
+type 'a t =
+  | No_info    of 'a
+  | Since      of 'a * Syntax.Version.t
+  | Deleted_in of 'a * Syntax.Version.t
+  | Renamed_in of Syntax.Version.t * string
+
+module Map = struct
+  type nonrec 'a t = 'a t String.Map.t
+
+  let values v                      = No_info (Kind.Values v)
+  let renamed_in ~new_name ~version = Renamed_in (version, new_name)
+  let deleted_in ~version kind      = Deleted_in (kind, version)
+  let since ~version v              = Since (v, version)
+
+  let static_vars =
+    [ "first-dep", since ~version:(1, 0) Kind.First_dep
+    ; "targets", since ~version:(1, 0) Kind.Targets
+    ; "deps", since ~version:(1, 0) Kind.Deps
+    ; "project_root", since ~version:(1, 0) Kind.Project_root
+
+    ; "<", renamed_in ~version:(1, 0) ~new_name:"first-dep"
+    ; "@", renamed_in ~version:(1, 0) ~new_name:"targets"
+    ; "^", renamed_in ~version:(1, 0) ~new_name:"deps"
+    ; "SCOPE_ROOT", renamed_in ~version:(1, 0) ~new_name:"project_root"
+    ]
+
+  let forms =
+    let form kind = No_info kind in
+    let open Form in
+    [ "exe", form Exe
+    ; "bin", form Bin
+    ; "lib", form Lib
+    ; "libexec", form Libexec
+    ; "lib-available", form Lib_available
+    ; "version", form Version
+    ; "read", form Read
+    ; "read-lines", form Read_lines
+    ; "read-strings", form Read_strings
+
+    ; "dep", since ~version:(1, 0) Dep
+
+    ; "path", renamed_in ~version:(1, 0) ~new_name:"dep"
+    ; "findlib", renamed_in ~version:(1, 0) ~new_name:"lib"
+
+    ; "path-no-dep", deleted_in ~version:(1, 0) Path_no_dep
+    ]
+    |> String.Map.of_list_exn
+
+  let create_vars ~(context : Context.t) ~cxx_flags =
+    let ocamlopt =
+      match context.ocamlopt with
+      | None -> Path.relative context.ocaml_bin "ocamlopt"
+      | Some p -> p
+    in
+    let string s = values [Value.String s] in
+    let path p = values [Value.Path p] in
+    let make =
+      match Bin.make with
+      | None   -> string "make"
+      | Some p -> path p
+    in
+    let cflags = context.ocamlc_cflags in
+    let strings s = values (Value.L.strings s) in
+    let lowercased =
+      [ "cpp"            , strings (context.c_compiler :: cflags @ ["-E"])
+      ; "cc"             , strings (context.c_compiler :: cflags)
+      ; "cxx"            , strings (context.c_compiler :: cxx_flags)
+      ; "ocaml"          , path context.ocaml
+      ; "ocamlc"         , path context.ocamlc
+      ; "ocamlopt"       , path ocamlopt
+      ; "arch_sixtyfour" , string (string_of_bool context.arch_sixtyfour)
+      ; "make"           , make
+      ; "root"           , values [Value.Dir context.build_dir]
+      ] in
+    let uppercased =
+      List.map lowercased ~f:(fun (k, _) ->
+        (String.uppercase k, renamed_in ~new_name:k ~version:(1, 0))) in
+    let vars =
+      [ "-verbose"       , values []
+      ; "pa_cpp"         , strings (context.c_compiler :: cflags
+                                    @ ["-undef"; "-traditional";
+                                       "-x"; "c"; "-E"])
+      ; "ocaml_bin"      , path context.ocaml_bin
+      ; "ocaml_version"  , string context.version_string
+      ; "ocaml_where"    , string (Path.to_string context.stdlib_dir)
+      ; "null"           , string (Path.to_string Config.dev_null)
+      ; "ext_obj"        , string context.ext_obj
+      ; "ext_asm"        , string context.ext_asm
+      ; "ext_lib"        , string context.ext_lib
+      ; "ext_dll"        , string context.ext_dll
+      ; "ext_exe"        , string context.ext_exe
+      ; "profile"        , string context.profile
+      ]
+    in
+    let ocaml_config =
+      List.map (Ocaml_config.to_list context.ocaml_config) ~f:(fun (k, v) ->
+        ("ocaml-config:" ^ k,
+         match (v : Ocaml_config.Value.t) with
+         | Bool   x -> string (string_of_bool x)
+         | Int    x -> string (string_of_int x)
+         | String x -> string x
+         | Words  x -> strings x
+         | Prog_and_args x -> strings (x.prog :: x.args)))
+    in
+    [ ocaml_config
+    ; static_vars
+    ; lowercased
+    ; uppercased
+    ; vars
+    ]
+    |> List.concat
+    |> String.Map.of_list_exn
+
+  let static_vars = String.Map.of_list_exn static_vars
+
+  let rec expand t ~syntax_version ~var =
+    let name = String_with_vars.Var.name var in
+    Option.bind (String.Map.find t name) ~f:(fun v ->
+      let what var =
+        sprintf "Variable %s" (String_with_vars.Var.to_string var) in
+      match v with
+      | No_info v -> Some v
+      | Since (v, min_version) ->
+        if syntax_version >= min_version then
+          Some v
+        else
+          Syntax.Error.since (String_with_vars.Var.loc var)
+            Stanza.syntax syntax_version
+            ~what:(what var)
+      | Renamed_in (in_version, new_name) -> begin
+          if syntax_version >= in_version then
+            let var =
+              if String_with_vars.Var.is_form var then
+                String_with_vars.Var.with_payload var ~payload:(Some "..")
+              else
+                var
+            in
+            Syntax.Error.renamed_in (String_with_vars.Var.loc var)
+              Stanza.syntax syntax_version
+              ~what:(what var)
+              ~to_:(let open String_with_vars.Var in
+                    to_string (with_name var ~name:new_name))
+          else
+            expand t ~syntax_version:in_version
+              ~var:(String_with_vars.Var.with_name var ~name:new_name)
+        end
+      | Deleted_in (v, in_version) ->
+        if syntax_version < in_version then
+          Some v
+        else
+          Syntax.Error.deleted_in (String_with_vars.Var.loc var)
+            Stanza.syntax syntax_version ~what:(what var))
+end
diff --git a/src/var.mli b/src/var.mli
new file mode 100644
index 00000000..06778460
--- /dev/null
+++ b/src/var.mli
@@ -0,0 +1,48 @@
+module Kind : sig
+  type t =
+    | Values of Value.t list
+    | Project_root
+    | First_dep
+    | Deps
+    | Targets
+
+  val to_value_no_deps_or_targets : t -> scope:Scope.t -> Value.t list option
+end
+
+module Form : sig
+  type t =
+    | Exe
+    | Dep
+    | Bin
+    | Lib
+    | Libexec
+    | Lib_available
+    | Version
+    | Read
+    | Read_strings
+    | Read_lines
+    | Path_no_dep
+end
+
+type 'a t =
+  | No_info    of 'a
+  | Since      of 'a * Syntax.Version.t
+  | Deleted_in of 'a * Syntax.Version.t
+  | Renamed_in of Syntax.Version.t * string
+
+module Map : sig
+  type 'a var
+  type 'a t
+
+  val create_vars : context:Context.t -> cxx_flags:string list -> Kind.t t
+
+  val forms : Form.t t
+
+  val static_vars : Kind.t t
+
+  val expand
+    :  'a t
+    -> syntax_version:Syntax.Version.t
+    -> var:String_with_vars.Var.t
+    -> 'a option
+end with type 'a var := 'a t