How about adding rational fraction to Python?

[Steven D'Aprano]

On Tue, 26 Feb 2008 21:41:16 -0800, Paul Rubin wrote:

> Mark Dickinson <dickinsm at gmail.com> writes:
>> > So use:  return sum(number_list) / float(len(number_list)) That makes
>> > it somewhat more explicit what you want.  Otherwise
>> 
>> But that fails for a list of Decimals...
> 
> Again, that depends on what your application considers to be failure.
> Heck, int/int = float instead of decimal might be a failure.
> 
> FWIW, I just checked Haskell: int/int is not allowed (compile time type
> error).  There is an integer division function `div`, like Python's //,
> . that you can use if you want an integer quotient. If you want a
> floating or rational quotient, you have to coerce the operands manually.
>  Explicit is better than implicit.

Argument by platitude now? I can play that game too. You forget that 
practicality beats purity.

When it comes to mixed arithmetic, it's just too darn inconvenient to 
forbid automatic conversions. Otherwise you end up either forbidding 
things like 1 + 1.0 on the basis that it isn't clear whether the 
programmer wants an int result or a float result, or else even more 
complex rules ("if the left operator is an int, and the result of the 
addition has a zero floating-point part, then the result is an int, 
otherwise it's an error, but if the left operator is a float, the result 
is always a float"). Or a proliferation of operators, with integer and 
floating point versions of everything.



-- 
Steven