Re: [Shootout] Spellcheck.adb

[Marius Amado Alves <amado.alves@netcabo.pt>]

At first sight the thing to improve is the hash function. The current 
function seems too expensive. Some time ago I had this problem. I 
invented a less expensive function with good dispersion. I don't have 
the code with me now, but it was as follows. Treat both the input and 
output values as bit strings X (1 .. M) and Y (1 .. N) respectively. 
(Use representation clauses, packed arrays, and unchecked conversion 
for this.) Make N small, say 16. Set Y bits to the value of X bits as 
follows:

if M > N, Y (J) = X (1 + (J - 1) * M / N), for J in 1 .. N

if M = N, Y = X

if M < N, initialize Y to all zeros,
  then let Y (1 + (I - 1) * N / M) = X (I), for I in 1 .. M

Another thing to improve may be the text input. Buffering with streams 
has proved faster than Text_IO.