X-Git-Url: https://git.hcoop.net/hcoop/domtool2.git/blobdiff_plain/63920aa5296a85edd9d734a65be22d9911358df2..e1b99e23f8d30efc7842ee006e0ff3ef0347b7df:/src/ast.sml

diff --git a/src/ast.sml b/src/ast.sml
index 91bca42..0e8688d 100644
--- a/src/ast.sml
+++ b/src/ast.sml
@@ -14,7 +14,7 @@
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
-*)
+ *)
 
 (* Configuration language abstract syntax *)
 
@@ -48,8 +48,18 @@ datatype typ' =
 	*  - Is valid in the given pred
 	*  - Expects an environment compatible with the first record
 	*  - Modifies it according to the second record *)
+       | TNested of pred * typ
+       (* Allow nested configuration, in the form of a function from an action
+	* satisfying the first predicate to an action satisfying the second and
+	* with the same environment variable IO behavior. *)
+
+       | TError
+       (* Marker that something already went wrong, so don't generate further
+	* error messages. *)
+       | TUnif of string * typ option ref
+       (* Unification variable to be determined during type-checking *)
 withtype typ = typ' * position
-     and record = typ StringMap.map
+     and record = (typ' * position) StringMap.map
 
 datatype exp' =
 	 EInt of int
@@ -59,23 +69,53 @@ datatype exp' =
        | EList of exp list
        (* Basic list constructor *)
 
-       | ELam of string * typ * exp
+       | ELam of string * typ option * exp
        (* Function abstraction *)
        | EVar of string
        (* Variable bound by a function *)
        | EApp of exp * exp
        (* Function application *)
 
+       | ESkip
+       (* Do-nothing action *)
        | ESet of string * exp
        (* Set an environment variable *)
        | EGet of string * string * exp
        (* Get an environment variable *)
        | ESeq of exp list
        (* Monad sequencer; execute a number of commands in order *)
-       | ELocal of exp
-       (* Local execution; execute the action and then restore the previous
-	* environment. *)
+       | ELocal of exp * exp
+       (* Local execution; like ESeq, but the writes of the first
+	* action are abandoned *)
+       | EWith of exp * exp
+       (* Apply a TNested to an action *)
+       | EALam of string * pred * exp
+       (* Abstraction for building TNested values *)
 withtype exp = exp' * position
 
+datatype decl' =
+	 DExternType of string
+       | DExternVal of string * typ
+       | DVal of string * typ option * exp
+       | DContext of string
+type decl = decl' * string option * position
+
+type file = string option * decl list * exp option
+
+fun multiApp (f, loc, args) =
+    foldl (fn (arg, e) => (EApp (e, arg), loc)) f args
+
+datatype unification_error =
+	 UnifyPred of pred * pred
+       | UnifyTyp of typ * typ
+       | UnifyOccurs of string * typ
+
+exception Unify of unification_error
+
+datatype type_error =
+	 WrongType of string * exp * typ * typ * unification_error option
+       | WrongForm of string * string * exp * typ * unification_error option
+       | UnboundVariable of string
+       | WrongPred of string * pred * pred
 
 end