On 2003-07-07 at 13:40+0200 Jerzy Karczmarczuk wrote:
[...] I believe (still naïvely??) that those socio-psycho-pragmatisms which played some role in the definition of the language should be better tuned. If I were to write
pi = 3.1415926536 :: Rational
I suppose that I would like to see rather 355/113 or something close, than 3926990817/1250000000 or similar.
If it's a _Rational_, surely you want it to be exactly the same as you get for 31415926536%10000000000?
GHCI doesn't make me happier than Hugs: 221069929751607/70368744177664.
That doesn't happen for me: Prelude> :m Ratio Prelude Ratio> 31415926536%10000000000 3926990817 % 1250000000 Prelude Ratio> 3.1415926536::Rational 3926990817 % 1250000000 Prelude Ratio> What did you do to get it?
Thus, perhaps one day we might think about parametrizing the 'conversion' of *explicit* decimal numbers, and -- as some other language permit -- make it possible and practical to use any other base different from 10. What do you think?
There might be a use for that, but one can already write 0x55%2^32 so I'm not sure that there would be much call for it, given what I say below
Such parametrization (perhaps with some global default) would also help the user who permits himself to write x = 1.875987 :: Rational to assess the error introduced by the representation conversion.
I think that <decimal number> :: Rational ought not to introduce any error at all! As to exact v inexact numbers, in a sense we already have that distinction. Integer and Rational are (in correct implementations!) exact, Int, Float and Double are inexact. One could express my objection to the design as: relegate all inexactitudes to libraries. Cheers, Jón -- Jón Fairbairn Jon.Fairbairn@cl.cam.ac.uk