ghc/lib/prelude/TyIO.hs

   1 module PreludeIO (
   2         Request(..), Response(..), IOError(..),
   3         Dialogue(..), SigAct(..),
   4         SuccCont(..), StrCont(..), StrListCont(..),
   5         BinCont(..), FailCont(..)
   6     ) where
   7
   8 import UTypes
   9
  10 -- Requests and responses:
  11
  12 data Request =  -- file system requests:
  13                           ReadFile      String
  14                         | WriteFile     String String
  15                         | AppendFile    String String
  16                         | ReadBinFile   String
  17                         | WriteBinFile  String Bin
  18                         | AppendBinFile String Bin
  19                         | DeleteFile    String
  20                         | StatusFile    String
  21                 -- channel system requests:
  22                         | ReadChan      String
  23                         | AppendChan    String String
  24                         | ReadBinChan   String
  25                         | AppendBinChan String Bin
  26                         | StatusChan    String
  27                 -- environment requests:
  28                         | Echo          Bool
  29                         | GetArgs
  30                         | GetProgName
  31                         | GetEnv        String
  32                         | SetEnv        String String
  33                         | SigAction     Int    SigAct
  34                 deriving () -- NB: Text
  35
  36 data SigAct =             SAIgnore
  37                         | SADefault
  38                         | SACatch Dialogue
  39
  40 data Response =           Success
  41                         | Str String
  42                         | StrList [String]
  43                         | Bn  Bin
  44                         | Failure IOError
  45                 deriving () -- NB: Text
  46
  47 data IOError =            WriteError   String
  48                         | ReadError    String
  49                         | SearchError  String
  50                         | FormatError  String
  51                         | OtherError   String
  52                         | EOD -- 1.3
  53                 deriving () -- NB: Text
  54
  55
  56 -- Continuation-based I/O:
  57
  58 type Dialogue    =  [Response] -> [Request]
  59 type SuccCont    =                Dialogue
  60 type StrCont     =  String     -> Dialogue
  61 type StrListCont =  [String]   -> Dialogue
  62 type BinCont     =  Bin        -> Dialogue
  63 type FailCont    =  IOError    -> Dialogue