beginning of my own HList with type families...

[hs-rrdtool.git] / Database / RRDtool.hs

diff --git a/Database/RRDtool.hs b/Database/RRDtool.hs
index 45ae91a3a36da7f675fca245a6de2c66abbcf07d..34867d0f19372ac2a80ec50a42feb1ae9944c086 100644 (file)
--- a/Database/RRDtool.hs
+++ b/Database/RRDtool.hs
@@ -1,6 +1,8 @@
 module Database.RRDtool
     ( DataSource(..)
 
+    , MentionedVars(..)
+
     , Expr
     , CommonExpr
     , IterativeExpr
@@ -10,7 +12,9 @@ module Database.RRDtool
     , CommonExprSet
 
     , Constant(..)
+    , VarName(..)
     , Variable(..)
+    , VariableSet
     , CommonUnaryOp(..)
     , CommonBinaryOp(..)
     , CommonTrinaryOp(..)
@@ -161,14 +165,15 @@ dsTest = COMPUTE {
            , dsExpr = AverageOf (Const 100 .*. Const 200 .*. HNil)
          }
 
+class VariableSet (MentionedVarsOf a) => MentionedVars a where
+    type MentionedVarsOf a
+
 class (Show e, Eq e) => Expr e
 class Expr e => CommonExpr e
 class Expr e => IterativeExpr e
 class Expr e => AggregativeExpr e
 instance CommonExpr e => IterativeExpr e
 
---class MentionedVars
-
 class (Show es, Eq es, HList es) => ExprSet es
 instance ExprSet HNil
 instance (Expr e, ExprSet es) => ExprSet (HCons e es)
@@ -185,12 +190,24 @@ data Constant
     deriving (Show, Eq, Ord)
 instance Expr Constant
 instance CommonExpr Constant
+instance MentionedVars Constant where
+    type MentionedVarsOf Constant = HNil
 
-class (Show a, Eq a) => Variable a where
+class (Show a, Eq a, Ord a) => VarName a where
     varName :: a -> String
 
-instance Variable a => Expr a
-instance Variable a => CommonExpr a
+data Variable vn
+    = Variable !vn
+    deriving (Show, Eq, Ord)
+
+instance VarName vn => Expr (Variable vn)
+instance VarName vn => CommonExpr (Variable vn)
+instance VarName vn => MentionedVars (Variable vn) where
+    type MentionedVarsOf (Variable vn) = vn :*: HNil
+
+class HList vs => VariableSet vs
+instance VariableSet HNil
+instance (VarName vn, VariableSet vs) => VariableSet (HCons vn vs)
 
 -- Common operators
 data CommonUnaryOp a
@@ -210,6 +227,8 @@ data CommonUnaryOp a
     deriving (Show, Eq, Ord)
 instance Expr a => Expr (CommonUnaryOp a)
 instance CommonExpr a => CommonExpr (CommonUnaryOp a)
+instance VariableSet (MentionedVarsOf a) => MentionedVars (CommonUnaryOp a) where
+    type MentionedVarsOf (CommonUnaryOp a) = MentionedVarsOf a
 
 data CommonBinaryOp a b
     = !a :<:  !b
@@ -228,10 +247,20 @@ data CommonBinaryOp a b
     | AddNaN !a !b
     | AtanXY !a !b
     deriving (Show, Eq, Ord)
-instance (Expr a, Expr b)
-    => Expr (CommonBinaryOp a b)
-instance (CommonExpr a, CommonExpr b)
-    => CommonExpr (CommonBinaryOp a b)
+
+instance (Expr a, Expr b) =>
+    Expr (CommonBinaryOp a b)
+
+instance (CommonExpr a, CommonExpr b) =>
+    CommonExpr (CommonBinaryOp a b)
+
+instance (VariableSet (MentionedVarsOf a),
+          VariableSet (MentionedVarsOf b),
+          VariableSet (HAppend (MentionedVarsOf a) (MentionedVarsOf b))) =>
+    MentionedVars (CommonBinaryOp a b) where
+        type MentionedVarsOf (CommonBinaryOp a b)
+            = HAppend (MentionedVarsOf a) (MentionedVarsOf b)
+        
 
 data CommonTrinaryOp a b c
     = If !a !b !c
@@ -251,30 +280,30 @@ data CommonSetOp es
 instance ExprSet es => Expr (CommonSetOp es)
 instance CommonExprSet es => CommonExpr (CommonSetOp es)
 
-data TrendOp v a
-    = Trend      !v !a
-    | TrendNan   !v !a
+data TrendOp vn a
+    = Trend      !(Variable vn) !a
+    | TrendNan   !(Variable vn) !a
     deriving (Show, Eq, Ord)
-instance (Variable v, Expr a) => Expr (TrendOp v a)
-instance (Variable v, CommonExpr a) => CommonExpr (TrendOp v a)
+instance (VarName vn, Expr a) => Expr (TrendOp vn a)
+instance (VarName vn, CommonExpr a) => CommonExpr (TrendOp vn a)
 
-data VariableShiftPredictOp ss w v
-    = VariableShiftPredictAverage !ss !w !v
-    | VariableShiftPredictSigma   !ss !w !v
+data VariableShiftPredictOp ss w vn
+    = VariableShiftPredictAverage !ss !w !(Variable vn)
+    | VariableShiftPredictSigma   !ss !w !(Variable vn)
     deriving (Show, Eq, Ord)
-instance (ExprSet ss, Expr w, Variable v)
-    => Expr (VariableShiftPredictOp ss w v)
-instance (CommonExprSet ss, CommonExpr w, Variable v)
-    => CommonExpr (VariableShiftPredictOp ss w v)
-
-data FixedShiftPredictOp sm w v
-    = FixedShiftPredictAverage !sm !w !v
-    | FixedShiftPredictSigma   !sm !w !v
+instance (ExprSet ss, Expr w, VarName vn)
+    => Expr (VariableShiftPredictOp ss w vn)
+instance (CommonExprSet ss, CommonExpr w, VarName vn)
+    => CommonExpr (VariableShiftPredictOp ss w vn)
+
+data FixedShiftPredictOp sm w vn
+    = FixedShiftPredictAverage !sm !w !(Variable vn)
+    | FixedShiftPredictSigma   !sm !w !(Variable vn)
     deriving (Show, Eq, Ord)
-instance (Expr sm, Expr w, Variable v)
-    => Expr (FixedShiftPredictOp sm w v)
-instance (CommonExpr sm, CommonExpr w, Variable v)
-    => CommonExpr (FixedShiftPredictOp sm w v)
+instance (Expr sm, Expr w, VarName vn)
+    => Expr (FixedShiftPredictOp sm w vn)
+instance (CommonExpr sm, CommonExpr w, VarName vn)
+    => CommonExpr (FixedShiftPredictOp sm w vn)
 
 -- Common special values
 data CommonValue
@@ -296,30 +325,30 @@ data IterativeValue
 instance Expr IterativeValue
 instance IterativeExpr IterativeValue
 
-data IterativeValueOf v
-    = PreviousOf !v
+data IterativeValueOf vn
+    = PreviousOf !(Variable vn)
     deriving (Show, Eq, Ord)
-instance Variable v => Expr (IterativeValueOf v)
-instance Variable v => IterativeExpr (IterativeValueOf v)
+instance VarName vn => Expr (IterativeValueOf vn)
+instance VarName vn => IterativeExpr (IterativeValueOf vn)
 
 -- Aggregative operators (fairly restricted due to rrdtool's
 -- restriction)
-data AggregativeUnaryOp v
-    = Maximum    !v
-    | Minimum    !v
-    | Average    !v
-    | StandardDeviation !v
-    | First      !v
-    | Last       !v
-    | Total      !v
-    | Percent    !v !Constant
-    | PercentNan !v !Constant
-    | LSLSlope   !v
-    | LSLInt     !v
-    | LSLCorrel  !v
+data AggregativeUnaryOp vn
+    = Maximum    !(Variable vn)
+    | Minimum    !(Variable vn)
+    | Average    !(Variable vn)
+    | StandardDeviation !(Variable vn)
+    | First      !(Variable vn)
+    | Last       !(Variable vn)
+    | Total      !(Variable vn)
+    | Percent    !(Variable vn) !Constant
+    | PercentNan !(Variable vn) !Constant
+    | LSLSlope   !(Variable vn)
+    | LSLInt     !(Variable vn)
+    | LSLCorrel  !(Variable vn)
     deriving (Show, Eq, Ord)
-instance Variable v => Expr (AggregativeUnaryOp v)
-instance Variable v => AggregativeExpr (AggregativeUnaryOp v)
+instance VarName vn => Expr (AggregativeUnaryOp vn)
+instance VarName vn => AggregativeExpr (AggregativeUnaryOp vn)
 
 -- |The 'createRRD' function lets you set up new Round Robin Database
 -- (RRD) files. The file is created at its final, full size and filled