diff options
| -rw-r--r-- | Runnable.hs | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/Runnable.hs b/Runnable.hs index f1bb16b..b6ed004 100644 --- a/Runnable.hs +++ b/Runnable.hs @@ -4,16 +4,16 @@ -- Module : Xmobar.Runnable -- Copyright : (c) Andrea Rossato -- License : BSD-style (see LICENSE) --- +-- -- Maintainer : Andrea Rossato <andrea.rossato@unibz.it> -- Stability : unstable -- Portability : unportable -- -- The existential type to store the list of commands to be executed. -- I must thank Claus Reinke for the help in understanding the mysteries of --- reading existential types. The Read instance of Runnable must be credited to --- him. --- +-- reading existential types. The Read instance of Runnable must be credited to +-- him. +-- -- See here: -- http:\/\/www.haskell.org\/pipermail\/haskell-cafe\/2007-July\/028227.html -- @@ -43,10 +43,10 @@ class ReadAsAnyOf ts ex where -- | Reads an existential type as any of hidden types ts readAsAnyOf :: ts -> ReadPrec ex -instance ReadAsAnyOf () ex where +instance ReadAsAnyOf () ex where readAsAnyOf ~() = mzero -instance (Show t, Read t, Exec t, ReadAsAnyOf ts Runnable) => ReadAsAnyOf (t,ts) Runnable where +instance (Show t, Read t, Exec t, ReadAsAnyOf ts Runnable) => ReadAsAnyOf (t,ts) Runnable where readAsAnyOf ~(t,ts) = r t `mplus` readAsAnyOf ts where r ty = do { m <- readPrec; return (Run (m `asTypeOf` ty)) } |