Параметр                               C         Haskell
--------------------------------------------------------
Затраченное процессорное время  сек    0.800     44.820
Размер object file              Kbyte  2.5       24.7
Размер executable file          Kbyte  6.1     1256.0

-- C code -----------------------------------
int main(){
  double   Amin, Amax, Bmin, Bmax, Ai, Bi, diff;
  double   Rsq   = 0.0;
  double   Anorm = 0.0;
  double   Bnorm = 0.0;
  unsigned i     = 0;
  FILE * input;
  input = fopen( "inp.txt", "r" );
  while( fscanf( input, "%lf %lf", &Ai, &Bi ) != EOF ){
    if( i > 0 ){
      if( Ai > Amax ) Amax = Ai; if( Ai < Amin ) Amin = Ai;
      if( Bi > Bmax ) Bmax = Bi; if( Bi < Bmin ) Bmin = Bi;
    } else {
      Amin = Amax = Ai, Bmin = Bmax = Bi;
    }
    i     += 1,
    diff   = Ai   - Bi,
    Rsq   += diff * diff,
    Anorm += Ai   * Ai,
    Bnorm += Bi   * Bi;
  }
  fclose( input );
  printf( "\n A range: %lf %lf; norm: %lf", Amin, Amax, sqrt( Anorm ) );
  printf( "\n B range: %lf %lf; norm: %lf", Bmin, Bmax, sqrt( Bnorm ) );
  printf( "\n Rsq:     %lf", sqrt( Rsq / i ) );
  return 0;
}

-- Haskell code -----------------------------------
import Data.List
process( !count, !amin, !amax, !bmin, !bmax, !asq, !bsq, !rsq )( a, b ) =
  ( count + 1, amin', amax', bmin', bmax', asq', bsq', rsq' )
  where
    amin'       = min amin a
    bmin'       = min bmin b
    amax'       = max amax a
    bmax'       = max bmax b
    addSq sum x = sum + x * x
    asq'        = addSq asq a
    bsq'        = addSq bsq b
    rsq'        = addSq rsq ( a - b )
main = do
  text <- readFile "inp.txt"
  let
    ws = words text
    ds :: [Double]
    ds = map read ws
    toPairs( a:b:abs ) = ( a, b ) : toPairs abs
    toPairs _ = []
    pairs = toPairs ds
    start = case pairs of
      ( ( a, b ) : _ ) ->  ( 0, a, a, b, b, 0, 0, 0 )
      _ -> error "empty input."
    ( count, amin, amax, bmin, bmax, asq, bsq, rsq ) = foldl' process start pairs
    norm x = sqrt x
  putStrLn $ "A range: " ++ show( amin, amax ) ++ "; norm " ++ show( norm asq )
  putStrLn $ "B range: " ++ show( bmin, bmax ) ++ "; norm " ++ show( norm bsq )
  putStrLn $ "R : "      ++ show( norm rsq )