diff --git a/src/Math/Haskellator.hs b/src/Math/Haskellator.hs
index e8418ed..6a9285f 100644
--- a/src/Math/Haskellator.hs
+++ b/src/Math/Haskellator.hs
@@ -1,6 +1,6 @@
 -- | Calculator module for evaluating mathematical expressions containing SI units
 
-module Math.Haskellator (EvalValue, calculate) where
+module Math.Haskellator (calculate) where
 
 import Control.Monad
 
@@ -9,12 +9,8 @@ import Math.Haskellator.Internal.AstProcessingSteps.Normalize
 import Math.Haskellator.Internal.Expr
 import Math.Haskellator.Internal.Lexer
 import Math.Haskellator.Internal.Parser
-import Math.Haskellator.Internal.Units
 import Math.Haskellator.Internal.Utils.Error
 
--- | The specific 'Value' type returned by the evaluation
-type EvalValue = Value Dimension
-
 getAst :: String -> Either Error Expr
 getAst = scan >=> parse >=> normalize
 
diff --git a/src/Math/Haskellator/Internal/AstProcessingSteps/Evaluate.hs b/src/Math/Haskellator/Internal/AstProcessingSteps/Evaluate.hs
index 1e85e0e..4c130bb 100644
--- a/src/Math/Haskellator/Internal/AstProcessingSteps/Evaluate.hs
+++ b/src/Math/Haskellator/Internal/AstProcessingSteps/Evaluate.hs
@@ -3,7 +3,8 @@
 -- | Evaluate the expression tree to a numeric value and a dimension.
 
 module Math.Haskellator.Internal.AstProcessingSteps.Evaluate (
-      evaluate
+      EvalValue
+    , evaluate
     , execute
     , mergeUnits
     , subtractUnits
@@ -18,6 +19,9 @@ import Math.Haskellator.Internal.Operators
 import Math.Haskellator.Internal.Units
 import Math.Haskellator.Internal.Utils.Error
 
+-- | The specific 'Value' type returned by the evaluation
+type EvalValue = Value Dimension
+
 -- | Evaluate an expression tree to a numeric value
 evaluate :: Expr                -- ^ the expression tree to evaluate
          -> Either Error Double -- ^ the numeric result or an error
@@ -25,18 +29,18 @@ evaluate expr = execute expr <&> value
 
 -- | Determine the result (value and dimension) of an expression tree
 execute :: Expr                           -- ^ the expression tree to evaluate
-        -> Either Error (Value Dimension) -- ^ the result or an error
+        -> Either Error EvalValue -- ^ the result or an error
 execute expr = do
     r <- runAstFold $ execute' expr
     return $ r { unit = filterZeroPower $ unit r }
 
-execute' :: Expr -> SimpleAstFold (Value Dimension)
+execute' :: Expr -> SimpleAstFold EvalValue
 execute' = partiallyFoldExprM execVal execBinOp execUnaryOp execConversion execVarBinds execVar
 
-execVal :: Value Dimension -> SimpleAstFold (Value Dimension)
+execVal :: EvalValue -> SimpleAstFold EvalValue
 execVal = return
 
-execBinOp :: Value Dimension -> Op -> Value Dimension -> SimpleAstFold (Value Dimension)
+execBinOp :: EvalValue -> Op -> EvalValue -> SimpleAstFold EvalValue
 execBinOp lhs Plus  rhs | unit lhs == unit rhs = return $ combineValues (+) lhs rhs
                         | otherwise = throwError $ Error RuntimeError $ "Cannot add units " ++ show (unit lhs) ++ " and " ++ show (unit rhs)
 execBinOp lhs Minus rhs | unit lhs == unit rhs = return $ combineValues (-) lhs rhs
@@ -54,20 +58,20 @@ execBinOp lhs Pow   rhs = case rhs of
     _          -> throwError $ Error RuntimeError "Exponentiation of units is not supported"
 execBinOp _   op    _   = throwError $ Error ImplementationError $ "Unknown binary operator " ++ show op
 
-execUnaryOp :: Op -> Value Dimension -> SimpleAstFold (Value Dimension)
+execUnaryOp :: Op -> EvalValue -> SimpleAstFold EvalValue
 execUnaryOp op rhs = case op of
     UnaryMinus -> return $ mapValue (0-) rhs
     _          -> throwError $ Error ImplementationError $ "Unknown unary operator " ++ show op
 
-execConversion :: Value Dimension -> Dimension -> SimpleAstFold (Value Dimension)
+execConversion :: EvalValue -> Dimension -> SimpleAstFold EvalValue
 execConversion _ _ = throwError $ Error ImplementationError "Conversion is handled elsewhere"
 
-execVarBinds :: Bindings Expr -> Expr -> SimpleAstFold (Value Dimension)
+execVarBinds :: Bindings Expr -> Expr -> SimpleAstFold EvalValue
 execVarBinds bs expr = runInNewScope $ do
     bindVars $ fmap Expr <$> bs
     execute' expr
 
-execVar :: String -> SimpleAstFold (Value Dimension)
+execVar :: String -> SimpleAstFold EvalValue
 execVar n = getVarBinding n >>= \case
     (Result v) -> return v
     (Expr e)   -> do