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Prelude and Libraries

• The Prelude exports the following classes and methods (which are also correctly exported from the Ix, Char and Ratio modules):
  • The class Ix(range, index, inRange, rangeSize).

  • ord, chr, isAscii, isControl, isPrint, isSpace, isUpper, isLower, isAlpha, isDigit, isOctDigit, isHexDigit, isAlphanum, toUpper, toLower, digitToInt, and intToDigit.

  • The types Ratio and Rational and the functions (%), numerator, denominator and approxRational.
  In addition:
  • The Num class has an additional method: fromInt.

  • The Integral class has two additional methods: odd and even.

  • The Fractional class has an additional method: fromDouble.

• The IO library doesn't export the following values: handlePosn, FileSize, ReadWriteMode, hSetBuffering, hGetBuffering, hSeek, hIsSeekable, hIsEOF, isEOF, hReady and hLookahead.

  The following non-standard functions are exported from IO:

    hugsGetCh :: IO Char   -- getchar without echoing to screen
    hugsHIsEOF :: Handle -> IO Bool
      -- same semantics as C's "feof" (different from Haskell's hIsEOF)
    hugsIsEOF  :: IO Bool
      -- same semantics as C's "feof(stdin)"
    hPutStrLn  :: String -> IO ()
      -- corresponds to Prelude.putStrLn
  

• The System library has the following differences:
  • Only the stand-alone system (runhugs) passes arguments to the executing program. The interactive system always uses an empty argument list when runnning a program. This affect the output of the functions getProgName and getArgs

  • When running under Windows 95, System.system always returns ExitSuccess.

The following libraries are not yet available: Directory, Time, Locale and CPUTime.