RWST.icl

   1 implementation module RWST
   2
   3 import StdTuple
   4
   5 from Data.Func import $
   6 import Data.Void
   7 import Data.Functor.Identity
   8 import Data.Functor
   9 import Data.Monoid
  10 import Control.Monad
  11 import Control.Applicative
  12
  13 // The RWS monad
  14 :: RWS r w s a :== RWST r w s Identity a
  15
  16 rws :: (r -> s -> (a, s, w)) -> RWS r w s a
  17 rws f = RWST \r s->Identity $ f r s
  18
  19 runRWS :: (RWS r w s a) r s -> (a, s, w)
  20 runRWS m r s = runIdentity $ runRWST m r s
  21
  22 evalRWS :: (RWS r w s a) r s -> (a, w)
  23 evalRWS m r s = let (a, _, w) = runRWS m r s in (a, w)
  24
  25 execRWS :: (RWS r w s a) r s -> (s, w)
  26 execRWS m r s = let (_, s`, w) = runRWS m r s in (s`, w)
  27
  28 mapRWS :: ((a, s, w) -> (b, s, w`)) (RWS r w s a) -> RWS r w` s b
  29 mapRWS f m = mapRWST (Identity o f o runIdentity) m
  30
  31 withRWS :: (r` s -> (r, s)) (RWS r w s a) -> RWS r` w s a
  32 withRWS f m = withRWST f m
  33
  34 // The RWST monad transformer
  35 :: RWST r w s m a = RWST (r s -> m (a, s, w))
  36
  37 instance Functor (RWST r w s m) | Monad m & Monoid w where
  38         fmap f m = liftM f m
  39
  40 instance Applicative (RWST r w s m) | Monad m & Monoid w where
  41     pure a = RWST \_ s->pure (a, s, mempty)
  42         (<*>) mf mx = ap mf mx
  43
  44 instance Monad (RWST r w s m) | Monad m & Monoid w where
  45         bind m k = RWST \r s->runRWST m r s
  46                 >>= \(a, s`, w)->runRWST (k a) r s`
  47                 >>= \(b, s``,w`)->pure (b, s``, mappend w w`)
  48
  49 runRWST :: (RWST r w s m a) r s -> m (a, s, w)
  50 runRWST (RWST f) r s = f r s
  51
  52 evalRWST :: (RWST r w s m a) r s -> m (a, w) | Monad m
  53 evalRWST m r s = runRWST m r s >>= \(a, _, w)->pure (a, w)
  54
  55 execRWST :: (RWST r w s m a) r s -> m (s, w) | Monad m
  56 execRWST m r s = runRWST m r s >>= \(_, s`, w)->pure (s, w)
  57
  58 mapRWST :: ((m (a, s, w)) -> n (b, s, w`)) (RWST r w s m a) -> RWST r w` s n b
  59 mapRWST f m = RWST \r s->f $ runRWST m r s
  60
  61 withRWST :: (r` -> s -> (r, s)) (RWST r w s m a) -> RWST r` w s m a
  62 withRWST f m = RWST \r s->uncurry (runRWST m) $ f r s
  63
  64 // Reader operations
  65 ask :: RWST r w s m r | Monoid w & Monad m
  66 ask = RWST \r s->pure (r, s, mempty)
  67
  68 local :: (r -> r) (RWST r w s m a) -> RWST r w s m a | Monoid w & Monad m
  69 local f m = RWST \r s->runRWST m (f r) s
  70
  71 asks :: (r -> a) -> RWST r w s m a | Monoid w & Monad m
  72 asks f = ask >>= \r->pure $ f r
  73
  74 // Writer operations
  75 tell :: w -> RWST r w s m Void | Monoid w & Monad m
  76 tell w = RWST \_ s->pure (Void, s,w)
  77
  78 listen :: (RWST r w s m a) -> RWST r w s m (a, w) | Monoid w & Monad m
  79 listen m = RWST \r s->runRWST m r s >>= \(a, s`, w)->pure ((a, w), s`, w)
  80
  81 pass :: (RWST r w s m (a, w -> w)) -> RWST r w s m a | Monoid w & Monad m
  82 pass m = RWST \r s->runRWST m r s >>= \((a, f), s`, w)->pure (a, s`, f w)
  83
  84 listens :: (w -> b) (RWST r w s m a) -> RWST r w s m (a, b)| Monoid w & Monad m
  85 listens f m = listen m >>= \(a, w)->pure (a, f w)
  86
  87 censor :: (w -> w) (RWST r w s m a) -> RWST r w s m a | Monoid w & Monad m
  88 censor f m = pass $ m >>= \a->pure (a, f)
  89
  90 // State operation
  91 get :: RWST r w s m s | Monoid w & Monad m
  92 get = RWST \_ s->pure (s, s, mempty)
  93
  94 put :: s -> RWST r w s m Void | Monoid w & Monad m
  95 put s = RWST \_ _->pure (Void, s, mempty)
  96
  97 modify :: (s -> s) -> RWST r w s m Void | Monoid w & Monad m
  98 modify f = get >>= \s->put $ f s
  99
 100 gets :: (s -> a) -> RWST r w s m a | Monoid w & Monad m
 101 gets f = get >>= \s->pure $ f s
 102
 103 // Lifting other operations
 104 liftCallCC :: ((((a,s,w) -> m (b,s,w)) -> m (a,s,w)) -> m (a,s,w)) ((a -> RWST r w s m b) -> RWST r w s m a) -> RWST r w s m a | Monoid w
 105 liftCallCC callCC f = RWST \r s->callCC
 106         \c->runRWST (f $ \a->RWST \_ _->c (a, s, mempty)) r s
 107
 108 liftCallCC` :: ((((a,s,w) -> m (b,s,w)) -> m (a,s,w)) -> m (a,s,w)) ((a -> RWST r w s m b) -> RWST r w s m a) -> RWST r w s m a | Monoid w
 109 liftCallCC` callCC f = RWST \r s->callCC
 110         \c->runRWST (f $ \a->RWST \_ s`->c (a, s`, mempty)) r s
 111
 112 liftCatch :: ((m (a,s,w)) (e -> m (a,s,w)) -> m (a,s,w)) (RWST l w s m a) (e -> RWST l w s m a) -> RWST l w s m a
 113 liftCatch catchError m h = RWST \r s->catchError
 114         (runRWST m r s) (\e->runRWST (h e) r s)