diff --git a/docs/React.md b/docs/React.md
index 27b9177..6de9af3 100644
--- a/docs/React.md
+++ b/docs/React.md
@@ -26,18 +26,10 @@ data EventHandler :: * -> *
 
 An event handler. The type argument represents the type of the event.
 
-#### `Disallowed`
-
-``` purescript
-data Disallowed
-```
-
-This phantom type indicates that both read and write access to a resource are disallowed.
-
 #### `Read`
 
 ``` purescript
-data Read write
+data Read :: !
 ```
 
 This phantom type indicates that read access to a resource is allowed.
@@ -45,23 +37,23 @@ This phantom type indicates that read access to a resource is allowed.
 #### `Write`
 
 ``` purescript
-data Write
+data Write :: !
 ```
 
 This phantom type indicates that write access to a resource is allowed.
 
-#### `Only`
+#### `Disallowed`
 
 ``` purescript
-data Only
+type Disallowed = () :: # !
 ```
 
-This phantom type indicates that only read access to a resource is allowed.
+An access synonym which indicates that neither read nor write access are allowed.
 
 #### `ReadWrite`
 
 ``` purescript
-type ReadWrite = Read Write
+type ReadWrite = (read :: Read, write :: Write)
 ```
 
 An access synonym which indicates that both read and write access are allowed.
@@ -69,7 +61,7 @@ An access synonym which indicates that both read and write access are allowed.
 #### `ReadOnly`
 
 ``` purescript
-type ReadOnly = Read Only
+type ReadOnly = (read :: Read)
 ```
 
 An access synonym which indicates that reads are allowed but writes are not.
@@ -77,19 +69,17 @@ An access synonym which indicates that reads are allowed but writes are not.
 #### `ReactState`
 
 ``` purescript
-data ReactState :: * -> * -> !
+data ReactState :: # ! -> !
 ```
 
 This effect indicates that a computation may read or write the component state.
 
-The first type argument is either `ReadWrite`, `ReadOnly` or `Disallowed` dependeding on the context.
-
-The second type argument is the type of the state of the component.
+The first type argument is a row of access types (`Read`, `Write`).
 
 #### `ReactProps`
 
 ``` purescript
-data ReactProps :: * -> !
+data ReactProps :: !
 ```
 
 This effect indicates that a computation may read the component props.
@@ -97,12 +87,12 @@ This effect indicates that a computation may read the component props.
 #### `ReactRefs`
 
 ``` purescript
-data ReactRefs :: * -> !
+data ReactRefs :: # ! -> !
 ```
 
 This effect indicates that a computation may read the component refs.
 
-The first type argument is either `ReadOnly` or `Disallowed` dependeding on the context.
+The first type argument is a row of access types (`Read`, `Write`).
 
 #### `Refs`
 
@@ -139,7 +129,7 @@ The type of keyboard events.
 #### `EventHandlerContext`
 
 ``` purescript
-type EventHandlerContext eff props state result = Eff (props :: ReactProps props, refs :: ReactRefs ReadOnly, state :: ReactState ReadWrite state | eff) result
+type EventHandlerContext eff props state result = Eff (props :: ReactProps, refs :: ReactRefs ReadOnly, state :: ReactState ReadWrite | eff) result
 ```
 
 A function which handles events.
@@ -147,7 +137,7 @@ A function which handles events.
 #### `Render`
 
 ``` purescript
-type Render props state eff = ReactThis props state -> Eff (props :: ReactProps props, refs :: ReactRefs Disallowed, state :: ReactState ReadOnly state | eff) ReactElement
+type Render props state eff = ReactThis props state -> Eff (props :: ReactProps, refs :: ReactRefs Disallowed, state :: ReactState ReadOnly | eff) ReactElement
 ```
 
 A render function.
@@ -155,7 +145,7 @@ A render function.
 #### `GetInitialState`
 
 ``` purescript
-type GetInitialState props state eff = ReactThis props state -> Eff (props :: ReactProps props, state :: ReactState Disallowed state, refs :: ReactRefs Disallowed | eff) state
+type GetInitialState props state eff = ReactThis props state -> Eff (props :: ReactProps, state :: ReactState Disallowed, refs :: ReactRefs Disallowed | eff) state
 ```
 
 A get initial state function.
@@ -163,7 +153,7 @@ A get initial state function.
 #### `ComponentWillMount`
 
 ``` purescript
-type ComponentWillMount props state eff = ReactThis props state -> Eff (props :: ReactProps props, state :: ReactState ReadWrite state, refs :: ReactRefs Disallowed | eff) Unit
+type ComponentWillMount props state eff = ReactThis props state -> Eff (props :: ReactProps, state :: ReactState ReadWrite, refs :: ReactRefs Disallowed | eff) Unit
 ```
 
 A component will mount function.
@@ -171,7 +161,7 @@ A component will mount function.
 #### `ComponentDidMount`
 
 ``` purescript
-type ComponentDidMount props state eff = ReactThis props state -> Eff (props :: ReactProps props, state :: ReactState ReadWrite state, refs :: ReactRefs ReadOnly | eff) Unit
+type ComponentDidMount props state eff = ReactThis props state -> Eff (props :: ReactProps, state :: ReactState ReadWrite, refs :: ReactRefs ReadOnly | eff) Unit
 ```
 
 A component did mount function.
@@ -179,7 +169,7 @@ A component did mount function.
 #### `ComponentWillReceiveProps`
 
 ``` purescript
-type ComponentWillReceiveProps props state eff = ReactThis props state -> props -> Eff (props :: ReactProps props, state :: ReactState ReadWrite state, refs :: ReactRefs ReadOnly | eff) Unit
+type ComponentWillReceiveProps props state eff = ReactThis props state -> props -> Eff (props :: ReactProps, state :: ReactState ReadWrite, refs :: ReactRefs ReadOnly | eff) Unit
 ```
 
 A component will receive props function.
@@ -187,7 +177,7 @@ A component will receive props function.
 #### `ShouldComponentUpdate`
 
 ``` purescript
-type ShouldComponentUpdate props state eff = ReactThis props state -> props -> state -> Eff (props :: ReactProps props, state :: ReactState ReadWrite state, refs :: ReactRefs ReadOnly | eff) Boolean
+type ShouldComponentUpdate props state eff = ReactThis props state -> props -> state -> Eff (props :: ReactProps, state :: ReactState ReadWrite, refs :: ReactRefs ReadOnly | eff) Boolean
 ```
 
 A should component update function.
@@ -195,7 +185,7 @@ A should component update function.
 #### `ComponentWillUpdate`
 
 ``` purescript
-type ComponentWillUpdate props state eff = ReactThis props state -> props -> state -> Eff (props :: ReactProps props, state :: ReactState ReadWrite state, refs :: ReactRefs ReadOnly | eff) Unit
+type ComponentWillUpdate props state eff = ReactThis props state -> props -> state -> Eff (props :: ReactProps, state :: ReactState ReadWrite, refs :: ReactRefs ReadOnly | eff) Unit
 ```
 
 A component will update function.
@@ -203,7 +193,7 @@ A component will update function.
 #### `ComponentDidUpdate`
 
 ``` purescript
-type ComponentDidUpdate props state eff = ReactThis props state -> props -> state -> Eff (props :: ReactProps props, state :: ReactState ReadOnly state, refs :: ReactRefs ReadOnly | eff) Unit
+type ComponentDidUpdate props state eff = ReactThis props state -> props -> state -> Eff (props :: ReactProps, state :: ReactState ReadOnly, refs :: ReactRefs ReadOnly | eff) Unit
 ```
 
 A component did update function.
@@ -211,7 +201,7 @@ A component did update function.
 #### `ComponentWillUnmount`
 
 ``` purescript
-type ComponentWillUnmount props state eff = ReactThis props state -> Eff (props :: ReactProps props, state :: ReactState ReadOnly state, refs :: ReactRefs ReadOnly | eff) Unit
+type ComponentWillUnmount props state eff = ReactThis props state -> Eff (props :: ReactProps, state :: ReactState ReadOnly, refs :: ReactRefs ReadOnly | eff) Unit
 ```
 
 A component will unmount function.
@@ -251,7 +241,7 @@ React class for components.
 #### `getProps`
 
 ``` purescript
-getProps :: forall props state eff. ReactThis props state -> Eff (props :: ReactProps props | eff) props
+getProps :: forall props state eff. ReactThis props state -> Eff (props :: ReactProps | eff) props
 ```
 
 Read the component props.
@@ -259,7 +249,7 @@ Read the component props.
 #### `getRefs`
 
 ``` purescript
-getRefs :: forall props state write eff. ReactThis props state -> Eff (refs :: ReactRefs (Read write) | eff) Refs
+getRefs :: forall props state access eff. ReactThis props state -> Eff (refs :: ReactRefs (read :: Read | access) | eff) Refs
 ```
 
 Read the component refs.
@@ -267,7 +257,7 @@ Read the component refs.
 #### `getChildren`
 
 ``` purescript
-getChildren :: forall props state eff. ReactThis props state -> Eff (props :: ReactProps props | eff) (Array ReactElement)
+getChildren :: forall props state eff. ReactThis props state -> Eff (props :: ReactProps | eff) (Array ReactElement)
 ```
 
 Read the component children property.
@@ -275,7 +265,7 @@ Read the component children property.
 #### `writeState`
 
 ``` purescript
-writeState :: forall props state eff. ReactThis props state -> state -> Eff (state :: ReactState ReadWrite state | eff) state
+writeState :: forall props state access eff. ReactThis props state -> state -> Eff (state :: ReactState (write :: Write | access) | eff) state
 ```
 
 Write the component state.
@@ -283,7 +273,7 @@ Write the component state.
 #### `readState`
 
 ``` purescript
-readState :: forall props state write eff. ReactThis props state -> Eff (state :: ReactState (Read write) state | eff) state
+readState :: forall props state access eff. ReactThis props state -> Eff (state :: ReactState (read :: Read | access) | eff) state
 ```
 
 Read the component state.
@@ -291,7 +281,7 @@ Read the component state.
 #### `transformState`
 
 ``` purescript
-transformState :: forall props state eff. ReactThis props state -> (state -> state) -> Eff (state :: ReactState ReadWrite state | eff) state
+transformState :: forall props state eff. ReactThis props state -> (state -> state) -> Eff (state :: ReactState ReadWrite | eff) state
 ```
 
 Transform the component state by applying a function.
diff --git a/src/React.purs b/src/React.purs
index cfc0dea..980d660 100644
--- a/src/React.purs
+++ b/src/React.purs
@@ -6,10 +6,9 @@ module React
 
   , EventHandler()
 
-  , Disallowed()
   , Read()
   , Write()
-  , Only()
+  , Disallowed()
   , ReadWrite()
   , ReadOnly()
 
@@ -74,38 +73,33 @@ foreign import data ReactThis :: * -> * -> *
 -- | An event handler. The type argument represents the type of the event.
 foreign import data EventHandler :: * -> *
 
--- | This phantom type indicates that both read and write access to a resource are disallowed.
-data Disallowed
-
 -- | This phantom type indicates that read access to a resource is allowed.
-data Read write
+foreign import data Read :: !
 
 -- | This phantom type indicates that write access to a resource is allowed.
-data Write
+foreign import data Write :: !
 
--- | This phantom type indicates that only read access to a resource is allowed.
-data Only
+-- | An access synonym which indicates that neither read nor write access are allowed.
+type Disallowed = () :: # !
 
 -- | An access synonym which indicates that both read and write access are allowed.
-type ReadWrite = Read Write
+type ReadWrite = (read :: Read, write :: Write)
 
 -- | An access synonym which indicates that reads are allowed but writes are not.
-type ReadOnly = Read Only
+type ReadOnly = (read :: Read)
 
 -- | This effect indicates that a computation may read or write the component state.
 -- |
--- | The first type argument is either `ReadWrite`, `ReadOnly` or `Disallowed` dependeding on the context.
--- |
--- | The second type argument is the type of the state of the component.
-foreign import data ReactState :: * -> * -> !
+-- | The first type argument is a row of access types (`Read`, `Write`).
+foreign import data ReactState :: # ! -> !
 
 -- | This effect indicates that a computation may read the component props.
-foreign import data ReactProps :: * -> !
+foreign import data ReactProps :: !
 
 -- | This effect indicates that a computation may read the component refs.
 -- |
--- | The first type argument is either `ReadOnly` or `Disallowed` dependeding on the context.
-foreign import data ReactRefs :: * -> !
+-- | The first type argument is a row of access types (`Read`, `Write`).
+foreign import data ReactRefs :: # ! -> !
 
 -- | The type of refs objects.
 foreign import data Refs :: *
@@ -136,26 +130,26 @@ type KeyboardEvent =
 
 -- | A function which handles events.
 type EventHandlerContext eff props state result =
-  Eff ( props :: ReactProps props
+  Eff ( props :: ReactProps
       , refs :: ReactRefs ReadOnly
-      , state :: ReactState ReadWrite state
+      , state :: ReactState ReadWrite
       | eff
       ) result
 
 -- | A render function.
 type Render props state eff =
   ReactThis props state ->
-  Eff ( props :: ReactProps props
+  Eff ( props :: ReactProps
       , refs :: ReactRefs Disallowed
-      , state :: ReactState ReadOnly state
+      , state :: ReactState ReadOnly
       | eff
       ) ReactElement
 
 -- | A get initial state function.
 type GetInitialState props state eff =
   ReactThis props state ->
-  Eff ( props :: ReactProps props
-      , state :: ReactState Disallowed state
+  Eff ( props :: ReactProps
+      , state :: ReactState Disallowed
       , refs :: ReactRefs Disallowed
       | eff
       ) state
@@ -163,8 +157,8 @@ type GetInitialState props state eff =
 -- | A component will mount function.
 type ComponentWillMount props state eff =
   ReactThis props state ->
-  Eff ( props :: ReactProps props
-      , state :: ReactState ReadWrite state
+  Eff ( props :: ReactProps
+      , state :: ReactState ReadWrite
       , refs :: ReactRefs Disallowed
       | eff
       ) Unit
@@ -172,8 +166,8 @@ type ComponentWillMount props state eff =
 -- | A component did mount function.
 type ComponentDidMount props state eff =
   ReactThis props state ->
-  Eff ( props :: ReactProps props
-      , state :: ReactState ReadWrite state
+  Eff ( props :: ReactProps
+      , state :: ReactState ReadWrite
       , refs :: ReactRefs ReadOnly
       | eff
       ) Unit
@@ -182,8 +176,8 @@ type ComponentDidMount props state eff =
 type ComponentWillReceiveProps props state eff =
    ReactThis props state ->
    props ->
-   Eff ( props :: ReactProps props
-       , state :: ReactState ReadWrite state
+   Eff ( props :: ReactProps
+       , state :: ReactState ReadWrite
        , refs :: ReactRefs ReadOnly
        | eff
        ) Unit
@@ -193,8 +187,8 @@ type ShouldComponentUpdate props state eff =
   ReactThis props state ->
   props ->
   state ->
-  Eff ( props :: ReactProps props
-      , state :: ReactState ReadWrite state
+  Eff ( props :: ReactProps
+      , state :: ReactState ReadWrite
       , refs :: ReactRefs ReadOnly
       | eff
       ) Boolean
@@ -204,8 +198,8 @@ type ComponentWillUpdate props state eff =
   ReactThis props state ->
   props ->
   state ->
-  Eff ( props :: ReactProps props
-      , state :: ReactState ReadWrite state
+  Eff ( props :: ReactProps
+      , state :: ReactState ReadWrite
       , refs :: ReactRefs ReadOnly
       | eff
       ) Unit
@@ -215,8 +209,8 @@ type ComponentDidUpdate props state eff =
   ReactThis props state ->
   props ->
   state ->
-  Eff ( props :: ReactProps props
-      , state :: ReactState ReadOnly state
+  Eff ( props :: ReactProps
+      , state :: ReactState ReadOnly
       , refs :: ReactRefs ReadOnly
       | eff
       ) Unit
@@ -224,8 +218,8 @@ type ComponentDidUpdate props state eff =
 -- | A component will unmount function.
 type ComponentWillUnmount props state eff =
   ReactThis props state ->
-  Eff ( props :: ReactProps props
-      , state :: ReactState ReadOnly state
+  Eff ( props :: ReactProps
+      , state :: ReactState ReadOnly
       , refs :: ReactRefs ReadOnly
       | eff
       ) Unit
@@ -267,22 +261,22 @@ spec' getInitialState renderFn =
 foreign import data ReactClass :: * -> *
 
 -- | Read the component props.
-foreign import getProps :: forall props state eff. ReactThis props state -> Eff (props :: ReactProps props | eff) props
+foreign import getProps :: forall props state eff. ReactThis props state -> Eff (props :: ReactProps | eff) props
 
 -- | Read the component refs.
-foreign import getRefs :: forall props state write eff. ReactThis props state -> Eff (refs :: ReactRefs (Read write) | eff) Refs
+foreign import getRefs :: forall props state access eff. ReactThis props state -> Eff (refs :: ReactRefs (read :: Read | access) | eff) Refs
 
 -- | Read the component children property.
-foreign import getChildren :: forall props state eff. ReactThis props state -> Eff (props :: ReactProps props | eff) (Array ReactElement)
+foreign import getChildren :: forall props state eff. ReactThis props state -> Eff (props :: ReactProps | eff) (Array ReactElement)
 
 -- | Write the component state.
-foreign import writeState :: forall props state eff. ReactThis props state -> state -> Eff (state :: ReactState ReadWrite state | eff) state
+foreign import writeState :: forall props state access eff. ReactThis props state -> state -> Eff (state :: ReactState (write :: Write | access) | eff) state
 
 -- | Read the component state.
-foreign import readState :: forall props state write eff. ReactThis props state -> Eff (state :: ReactState (Read write) state | eff) state
+foreign import readState :: forall props state access eff. ReactThis props state -> Eff (state :: ReactState (read :: Read | access) | eff) state
 
 -- | Transform the component state by applying a function.
-transformState :: forall props state eff. ReactThis props state -> (state -> state) -> Eff (state :: ReactState ReadWrite state | eff) state
+transformState :: forall props state eff. ReactThis props state -> (state -> state) -> Eff (state :: ReactState ReadWrite | eff) state
 transformState ctx f = do
   state <- readState ctx
   writeState ctx $ f state
diff --git a/test/Main.purs b/test/Main.purs
index 271eeba..32c266e 100644
--- a/test/Main.purs
+++ b/test/Main.purs
@@ -5,7 +5,6 @@ import Prelude
 import Control.Monad.Eff
 import Control.Monad.Eff.Console
 
-import Data.Maybe (Maybe(..))
 import Data.Maybe.Unsafe (fromJust)
 import Data.Nullable (toMaybe)
 
@@ -29,6 +28,7 @@ foreign import interval :: forall eff a.
                              Eff eff a ->
                              Eff eff Unit
 
+hello :: forall props. ReactClass { name :: String | props }
 hello = createClass $ spec unit \ctx -> do
   props <- getProps ctx
   return $ D.h1 [ P.className "Hello"
@@ -38,6 +38,7 @@ hello = createClass $ spec unit \ctx -> do
                 , D.text props.name
                 ]
 
+counter :: forall props. ReactClass props
 counter = createClass counterSpec
   where
   counterSpec = (spec 0 render)
@@ -58,7 +59,8 @@ counter = createClass counterSpec
                       , D.text " Click me to increment!"
                       ]
 
-main = body' >>= render ui
+main :: forall eff. Eff (dom :: DOM | eff) Unit
+main = void (body' >>= render ui)
   where
   ui :: ReactElement
   ui = D.div' [ createFactory hello { name: "World" }
@@ -69,7 +71,7 @@ main = body' >>= render ui
                               ]
               ]
 
-  body' :: forall eff. Eff (dom :: DOM | eff) Element
+  body' :: Eff (dom :: DOM | eff) Element
   body' = do
     win <- window
     doc <- document win