if as an operator?

Giorgi Lekishvili gleki at gol.ge
Fri Jan 11 03:02:10 CET 2002


Yes! Otherwise I would have to learn scheme...
But now I'm saved:)

Robin Munn wrote:

> On Thu, 10 Jan 2002 15:37:41 -0800, Giorgi Lekishvili <gleki at gol.ge> wrote:
> >Hi!
> >
> >As most of us knows, scheme programming language presents a function as
> >a list.
> >
> >On a grate scale, our Python has many features of a functional
> >programming language, and first of all, that's the support of the lambda
> >calculus.
> >
> >If we apply the operator module, we can also present a simple function
> >as a list:
> >
> >>>> import operator as o
> >>>> add=o.add
> >>>> sub=o.sub
> >>>> div=o.div
> >>>> a,b,c=3,5,7
> >>>> f=[add,a,[sub,b,c]]
> >>>> f
> >[<built-in function add>, 3, [<built-in function sub>, 5, 7]]
> >>>> print f[0](f[1],f[2][0](f[2][1],f[2][2]))
> >1
> >>>>  f[2][0]=div
> >>>> print f[0](f[1],f[2][0](f[2][1],f[2][2]))
> >3
> >>>> f[2][1]=5.0
> >>>> print f[0](f[1],f[2][0](f[2][1],f[2][2]))
> >3.71428571429
> >>>>
> >
> >That means that Python can be very successfully employed for the
> >Gennetic Programming, if only one could have at hand 'if' as the
> >operator, e.g., like this:
> >>>> if_=o.if         #doesn't work now, of course
> >Even more important is to make comparisons in this vay:
> >>>> more_=o.more        # a would-be analog of '>'
> >>>>less_=o.less            # a would-be analog of '<'
> >etc.
> >
> >Of course, we can use operator.truth instead of 'if', but how about the
> >comparison?
> >
> >Mayba, I have missed something?
>
> Do the lt(a,b), le(a,b), eq(a,b), ... functions in the operator module
> not do what you want? Ah, I just saw in the Python documentation that
> these functions are new in Python 2.2. So it looks like you have your
> wish now. Just upgrade to version 2.2 and all your problems will be
> solved! :)
>
> >
> >
> >I believ that the complete, though optional support of functional
> >programming in Python would make it even more powerful and useful.
> >
> >I am familiar with the basics of compiler/interpreter design, but 'm a
> >chemist, working in the field of data analysis, not a programmer, as you
> >have surely noticed:)
> >
> >Greetings,
> >Giorgi
> >
> >
> >
> >
>
> --
> Robin Munn
> rmunn at pobox.com




More information about the Python-list mailing list