Re: Definable operators

andy@cs.Stanford.EDU (Andy Freeman) writes:
  > Yes, I think that definiable operators are worse than poorly chosen
  > value reference names. Definable operators share the "what is that?"
  > property of poorly chosen names, but they also have a "what is it
  > operating on?" problem.


Clear operator names help a lot and may even make the program clearer.
For instance, I once cooperated in the creation of a set of Algol 68
operators in numerical analysis. For instance, the integral from
0 to 1 of exp(x)^2dx with an absolute error bound of 1.0e-5 and a
relative error bound of 1.0e-6 would be written as:


        c := 'range' (0, 1) 'integral' (('real' x) 'real': exp(x) ** 2)
'abserr' 1.0e-5 'relerr' 1.0e-6;


Adding "'method' gauss(10)" would modify it to a 10-point gaussian
integration.


Why is the first not clearer than (also in Algol 68)


        c := integrate(0, 1, ('real' x) 'real': exp(x) ** 2, 1.0e-5, 1.0e-6)


which at least neads some comments to be made clear?


A good choice for the priorities is of course important. A bad choice
can be just as misleading as a badly chosen identifier.


--
dik t. winter, cwi, kruislaan 413, 1098 sj amsterdam, nederland, +31205924131
home: bovenover 215, 1025 jn amsterdam, nederland; http://www.cwi.nl/~dik/
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