-- Hoogle documentation, generated by Haddock
-- See Hoogle, http://www.haskell.org/hoogle/


-- | Framework for defaulting superclasses
--   
--   Framework for defaulting superclasses
@package impl
@version 0.1.0.0


-- | This small but extensible framework facilitates defining complex
--   defaulting rules that are not handled by <tt>DefaultSignatures</tt>,
--   and reducing the overhead of giving instances to new datatypes by
--   generating superclasses. One reason we might want this is when a
--   superclass wants to be given a default by two different subclasses
--   (ex: <tt>Bifunctor</tt> and <tt>Profunctor</tt> both could generate
--   <tt>Functor</tt> instances). See the <tt>example</tt> internal library
--   for how to implement instances of <a>Impl</a>.
module Impl
class Impl c where {
    type family Methods c :: [Symbol];
}

-- | Instantiate the implementing class along with all its superclasses Ex:
--   
--   <pre>
--   impl @Monad [t|[]|]
--     ! #return [|\x -&gt; [x]|]
--     ! #bind   [|flip concatMap|]
--   </pre>
impl :: Impl c => TypeQ -> NamedMethods c :-> DecsQ

-- | <a>Named</a> TH <a>Exp</a>s for the class method implementations
type NamedMethods c = NamedExpQ (Methods c)

-- | Converts a variable number of arguments into curried form. Ex:
--   
--   <pre>
--   &gt;&gt;&gt; :!kind '[Int,String,Double] :-&gt; IO ()
--   Int -&gt; String -&gt; Double -&gt; IO ()
--   </pre>
type family as :-> r
infixr 0 :->
type TypeQ = Q Type

-- | Supply a parameter to a function:
--   
--   <pre>
--   function <a>!</a> #param_name value
--   </pre>
--   
--   <pre>
--   function <a>!</a> #x 7 <a>!</a> #y 42 <a>!</a> <a>defaults</a>
--   </pre>
--   
--   This is an infix version of <a>with</a>.
(!) :: WithParam p fn fn' => fn -> Param p -> fn'
infixl 9 !

-- | Infix notation for the type of a named parameter.
type (:!) (name :: Symbol) a = NamedF Identity a name

-- | Assign a name to a value of type <tt>a</tt> wrapped in <tt>f</tt>.
--   
--   <pre>
--   #verbose True :: NamedF Identity Bool "verbose"
--   </pre>
data NamedF (f :: Type -> Type) a (name :: Symbol)

-- | <a>arg</a> unwraps a named parameter with the specified name. One way
--   to use it is to match on arguments with <tt>-XViewPatterns</tt>:
--   
--   <pre>
--   fn (arg #t -&gt; t) (arg #f -&gt; f) = ...
--   </pre>
--   
--   This way, the names of parameters can be inferred from the patterns:
--   no type signature for <tt>fn</tt> is required. In case a type
--   signature for <tt>fn</tt> is provided, the parameters must come in the
--   same order:
--   
--   <pre>
--   fn :: "t" :! Integer -&gt; "f" :! Integer -&gt; ...
--   fn (arg #t -&gt; t) (arg #f -&gt; f) = ... -- ok
--   fn (arg #f -&gt; f) (arg #t -&gt; t) = ... -- does not typecheck
--   </pre>
arg :: () => Name name -> (name :! a) -> a