X-Git-Url: https://git.hcoop.net/hcoop/domtool2.git/blobdiff_plain/a22c187b7b983dad6b0e2c34cd0ab74e95c2411b..dac62e84b324d2187ec9b9882efa47125d5599a4:/src/ast.sml

diff --git a/src/ast.sml b/src/ast.sml
index 6ee4b7b..efc2fb0 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 *)
 
@@ -23,18 +23,18 @@ structure Ast = struct
 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
@@ -43,11 +43,21 @@ datatype typ' =
        (* 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
 
@@ -59,23 +69,34 @@ 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 *)
-       | EEnv of string
+       | 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 *)
 withtype exp = exp' * position
 
+datatype decl' =
+	 DExternType of string
+       | DExternVal of string * typ
+       | DVal of string * typ option * exp
+type decl = decl' * string option * position
+
+type file = decl list * exp option
 
 end