@@ -6,8 +6,9 @@
  */
 module polemy.ast;
 import polemy._common;
 import polemy.failure;
+import polemy.layer;
 
 ///
 abstract class AST
 {
@@ -15,45 +16,46 @@
 	mixin SimpleConstructor;
 	mixin SimplePatternMatch;
 }
 
+///
+class IntLiteral : AST
+{
+	BigInt data;
+	mixin SimpleClass;
+	this(LexPosition pos, int n) {super(pos); data = n;}
+	this(LexPosition pos, long n) {super(pos); data = n;}
+	this(LexPosition pos, BigInt n) {super(pos); data = n;}
+	this(LexPosition pos, string n) {super(pos); data = BigInt(n);}
+}
+
 ///
 class StrLiteral : AST
 {
 	string data;
 	mixin SimpleClass;
 }
 
-///
-class IntLiteral : AST
-{
-	BigInt data;
-	mixin SimpleClass;
-	this(immutable LexPosition pos, long n) {super(pos); data = n;}
-	this(immutable LexPosition pos, BigInt n) {super(pos); data = n;}
-	this(immutable LexPosition pos, string n) {super(pos); data = BigInt(n);}
-}
-
 ///
 class VarExpression : AST
 {
-	string var;
+	string name;
 	mixin SimpleClass;
 }
 
 ///
-class LayeredExpression : AST
+class LayExpression : AST
 {
-	string lay;
-	AST    expr;
+	Layer layer;
+	AST   expr;
 	mixin SimpleClass;
 }
 
 ///
 class LetExpression : AST
 {
-	string var;
-	string layer;
+	string name;
+	Layer  layer;
 	AST    init;
 	AST    expr;
 	mixin SimpleClass;
 }
@@ -62,18 +64,18 @@
 class FuncallExpression : AST
 {
 	AST   fun;
 	AST[] args;
-	this(immutable LexPosition pos, AST fun, AST[] args...)
+	this(LexPosition pos, AST fun, AST[] args...)
 		{ super(pos); this.fun=fun; this.args=args.dup; }
 	mixin SimpleClass;
 }
 
 ///
 class Parameter
 {
-	string   name;
-	string[] layers;
+	string  name;
+	Layer[] layers;
 	mixin SimpleClass;
 }
 
 ///
@@ -98,9 +100,9 @@
 	auto fun(string[] xs, AST ps) {
 		return genEast!FunLiteral(array(map!((string x){return new Parameter(x,[]);})(xs)),ps); }
 	auto funp(Parameter[] xs, AST ps) { return genEast!FunLiteral(xs,ps); } ///
 	alias genEast!VarExpression var; ///
-	alias genEast!LayeredExpression lay; ///
+	alias genEast!LayExpression lay; ///
 	alias genEast!LetExpression let; ///
 	alias genEast!FuncallExpression call; ///
 	auto param(string name, string[] lay...) { return new Parameter(name, lay); } ///
 }