tock-mirror/polyplate/Data/Generics/Polyplate/Schemes.hs

123 lines
5.1 KiB
Haskell

{-
Tock: a compiler for parallel languages
Copyright (C) 2008 University of Kent
This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation, either version 2 of the License, or (at your
option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License along
with this program. If not, see <http://www.gnu.org/licenses/>.
-}
module Data.Generics.Polyplate.Schemes where
import Data.Generics.Polyplate
-- | Given a list of operations and a modifier function, augments that modifier
-- function to first descend into the value before then applying the modifier function.
-- This can be used to perform a bottom-up depth-first traversal of a structure
-- (see 'applyBottomUpM').
makeBottomUpM :: PolyplateM t () opT m => opT -> (t -> m t) -> t -> m t
makeBottomUpM ops f v = makeDescendM ops v >>= f
-- | Given a list of operations and a modifier function, augments that modifier
-- function to first apply the modifier function before then descending into the value.
-- This can be used to perform a top-down depth-first traversal of a structure
-- (see 'applyTopDownM').
makeTopDownM :: PolyplateM t () opT m => opT -> (t -> m t) -> t -> m t
makeTopDownM ops f v = f v >>= makeDescendM ops
-- | Given a list of operations and a modifier function, augments that modifier
-- function to first descend into the value before then applying the modifier function.
-- This can be used to perform a bottom-up depth-first traversal of a structure
-- (see 'applyBottomUp').
makeBottomUp :: Polyplate t () opT => opT -> (t -> t) -> t -> t
makeBottomUp ops f v = f (makeDescend ops v)
-- | Given a list of operations and a modifier function, augments that modifier
-- function to first apply the modifier function before then descending into the value.
-- This can be used to perform a top-down depth-first traversal of a structure
-- (see 'applyTopDown').
makeTopDown :: Polyplate t () opT => opT -> (t -> t) -> t -> t
makeTopDown ops f v = makeDescend ops (f v)
{- TODO
makeCheckM :: PolyplateM t () opT m => opT -> (t -> m ()) -> t -> m t
makeCheckM ops f v
= do v' <- descend v
f v'
return v'
where
descend = makeDescend ops
-}
-- TODO also add a listify-like thing (maybe return a rose tree):
-- applyQuery :: (s -> a) -> t -> Tree a
-- | Given a monadic function that applies to a particular type (s), automatically
-- applies that function to every instance of s in a larger structure of type t,
-- performing the transformations in a bottom-up fashion. It does a depth first
-- traversal in order of a constructor's children (assuming you are using one of
-- the generated instances, not your own), descending first and applying the function
-- afterwards on the way back up.
applyBottomUpM :: (PolyplateM t (OneOpM m s) () m,
PolyplateM s () (OneOpM m s) m) =>
(s -> m s) -> t -> m t
applyBottomUpM f = makeRecurseM ops
where
ops = baseOp `extOpM` makeBottomUpM ops f
-- | Given a monadic function that applies to a particular type (s), automatically
-- applies that function to every instance of s in a larger structure of type t,
-- performing the transformations in a top-down fashion. It does a depth first
-- traversal in order of a constructor's children (assuming you are using one of
-- the generated instances, not your own), applying the function first and then
-- descending.
applyTopDownM :: (PolyplateM t (OneOpM m s) () m,
PolyplateM s () (OneOpM m s) m) =>
(s -> m s) -> t -> m t
applyTopDownM f = makeRecurseM ops
where
ops = baseOp `extOpM` makeTopDownM ops f
-- | As applyBottomUpM, but applies two functions. These should not be modifying
-- the same type.
applyBottomUpM2 :: (PolyplateM t (TwoOpM m sA sB) () m,
PolyplateM sA () (TwoOpM m sA sB) m,
PolyplateM sB () (TwoOpM m sA sB) m
) =>
(sA -> m sA) -> (sB -> m sB) -> t -> m t
applyBottomUpM2 fA fB = makeRecurseM ops
where
ops = baseOp `extOpM` makeBottomUpM ops fA `extOpM` makeBottomUpM ops fB
-- | As applyTopDownM, but applies two functions. These should not be modifying
-- the same type.
applyTopDownM2 :: (PolyplateM t (TwoOpM m sA sB) () m,
PolyplateM sA () (TwoOpM m sA sB) m,
PolyplateM sB () (TwoOpM m sA sB) m
) =>
(sA -> m sA) -> (sB -> m sB) -> t -> m t
applyTopDownM2 fA fB = makeRecurseM ops
where
ops = baseOp `extOpM` makeTopDownM ops fA `extOpM` makeTopDownM ops fB
{- TODO
checkDepthM :: (Polyplate m (s -> m s, ()) () t,
Polyplate m () (s -> m s, ()) s) =>
(s -> m ()) -> t -> m t
checkDepthM f = makeRecurse ops
where
ops = baseOp `extOp` makeCheck ops f
-}