* 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 *)
open DataStructures
(* A description of a predicate on configuration block stacks *)
-datatype context' =
+datatype pred' =
CRoot
(* The stack is empty. *)
| CConst of string
- (* The given context name is on top of the stack. *)
- | CPrefix of context
- (* Some prefix of the stack matches the context. *)
- | CNot of context
- (* The context does not match. *)
- | CAnd of context * context
- (* Both contexts match. *)
-withtype context = context' * position
+ (* The given pred name is on top of the stack. *)
+ | CPrefix of pred
+ (* Some prefix of the stack matches the pred. *)
+ | CNot of pred
+ (* The pred does not match. *)
+ | CAnd of pred * pred
+ (* Both preds match. *)
+withtype pred = pred' * position
datatype typ' =
TBase of string
(* SML 'a list *)
| TArrow of typ * typ
(* SML -> *)
- | TAction of context * record * record
+ | TAction of pred * record * record
(* An action that:
- * - Is valid in the given context
+ * - 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
| 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