ghc-mod- Happy Haskell Programming

Safe HaskellNone



type CacheContents d a = Maybe (ModTime, [FilePath], d, a) Source #

type CacheLens s d a = s :-> CacheContents d a Source #

data Cached m s d a Source #




  • cacheFile :: FilePath
  • cacheLens :: Maybe (CacheLens s d a)
  • cachedAction :: TimedCacheFiles -> d -> Maybe a -> m ([FilePath], a)
    cachedAction tcf data ma
    • tcf: Input file timestamps. Not technically necessary, just an optimizazion when knowing which input files changed can make updating the cache faster
    • data: Arbitrary static input data to cache action. Can be used to invalidate the cache using something other than file timestamps i.e. environment tool version numbers
    • ma: Cached data if it existed


    • fst: Input files used in generating the cache
    • snd: Cache data, will be stored alongside the static input data in the cacheFile

    The cached action, will only run if one of the following is true:

    • cacheFile doesn't exist yet
    • cacheFile exists and inputData changed
    • any files returned by the cached action changed