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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 | -- Hoogle documentation, generated by Haddock
-- See Hoogle, http://www.haskell.org/hoogle/
-- | Generate default function implementations for complex type classes.
--
-- Template Haskell code to implement default implementations for
-- type-class functions based on which functions are already implemented.
-- Currently extremely crude but still fairly effective.
--
-- When defining a type class with many functions, each of which can be
-- implemented based on arbitrary subsets of the others, the standard
-- default-implementation concept breaks down quite badly. This library
-- provides a system by which more complex rules can be described for
-- choosing default implementations based on which ones the user
-- supplies. These implementations can additionally be given "suitability
-- scores", so that when multiple possible choices could be made, the
-- library can choose the "best" one.
--
-- Changes in 0.0.1.0: Updated for Template Haskell changes in GHC 7.6
--
-- Changes in v0.0.0.3: Added a hack to fix under GHC 7.2.
--
-- Changes in v0.0.0.2: Nothing at all except setting 'buildable: False'
-- under GHC 7.2.1.
@package flexible-defaults
@version 0.0.1.1
-- | A code-generation system for complex typeclass default-implementation
-- configurations. There are usage examples in this package's source
-- distribution[1] and in the random-source package[2].
--
-- <ol>
--
-- <li><a>https://github.com/mokus0/flexible-defaults/tree/master/examples</a></li>
--
-- <li><a>https://github.com/mokus0/random-fu/blob/master/random-source/src/Data/Random/Internal/TH.hs</a></li>
-- </ol>
module Language.Haskell.TH.FlexibleDefaults
-- | A description of a system of <a>Function</a>s and default
-- <a>Implementation</a>s which can be used to complete a partial
-- implementation of some type class.
data Defaults s a
-- | Map a function over all scores. This function's name comes from the
-- following idiom (where <a>Sum</a> is replaced by whatever
-- monoid-constructor you want to use to combine scores):
--
-- <pre>
-- foo = scoreBy Sum $ do
-- ...
-- </pre>
scoreBy :: (a -> b) -> Defaults a t -> Defaults b t
-- | A representation of a function for which one or more default
-- <a>Implementation</a>s exist. Defined using the <a>function</a>
-- function.
data Function s a
-- | Declare a function that must be implemented, and provide a description
-- of any default implementations which can be used.
function :: String -> Function s a -> Defaults s a
-- | State that a function must be implemented but has no default
-- implementation.
requireFunction :: String -> Defaults s ()
-- | A representation of a single possible implementation of a
-- <a>Function</a>. Defined using the <a>implementation</a> function.
data Implementation s a
-- | Describe a default implementation of the current function
implementation :: Implementation s (Q [Dec]) -> Function s ()
-- | Specify the score associated with the current implementation. Only one
-- invocation of either <a>score</a> or <a>cost</a> may be used per
-- implementation.
score :: s -> Implementation s ()
-- | Specify the cost (negated score) associated with the current
-- implementation. Only one invocation of either <a>score</a> or
-- <a>cost</a> may be used per implementation.
cost :: Num s => s -> Implementation s ()
-- | Specify that the current implementation must not be used unless the
-- given function is already defined. If this implementation can be used
-- mutually-recursively with _ALL_ potential implementations of some
-- other function, then a dependency need not be declared on that
-- function.
dependsOn :: String -> Implementation s ()
-- | Specify that an <a>Implementation</a> should be annotated with an
-- INLINE pragma. Under GHC versions earlier than 6.12 this is a no-op,
-- because those Template Haskell implementations do not support pragmas.
inline :: Implementation s ()
-- | Specify that an <a>Implementation</a> should be annotated with a
-- NOINLINE pragma. Under GHC versions earlier than 6.12 this is a no-op,
-- because those Template Haskell implementations do not support pragmas.
noinline :: Implementation s ()
-- | Given a <tt>Q [Dec]</tt> containing an instance declaration, complete
-- that instance declaration using the given <a>Defaults</a>
-- specification. Typical usage would be along the lines of the
-- following:
--
-- <pre>
-- $(withDefaults fooDefaults [d| instance Foo t where {- ... -} |])
-- </pre>
withDefaults :: (Monoid s, Ord s) => Defaults s () -> Q [Dec] -> Q [Dec]
-- | Given a partial list of function declarations, complete that list
-- based on the <a>Defaults</a> specification given.
implementDefaults :: (Ord s, Monoid s) => Defaults s () -> [Dec] -> Q [Dec]
|