eval1 :: (Show a, Eq a, Field a, Exponentiative a, Applicable a) => String -> a -> Expression a -> a
eval1 name value exp0 =
  map0
    (\vName ->
       if name == vName
         then value
         else undefined)
    id
    undefined
    fnValue
    exp0
eval1 :: (Show a, Eq a, Field a, Exponentiative a, Applicable a) => String -> a -> Expression a -> a
eval1 name value exp0 =
  map0
    (\vName ->
       if name == vName
         then value
         else undefined)
    id
    undefined
    fnValue
    exp0
eval1 name value exp0 =
  map0
    (\vName ->
       if name == vName
         then value
         else undefined)
    id
    undefined
    fnValue
    exp0