> I don't think "trivial" is the right word to use here,
> since it implies something that's of so little importance
> that it can be ignored. But the simple cases are precisely
> the ones where this wart hurts the most, so we can't
> ignore them.
I'd like to inject an example that might help make this discussion more
concrete.
Consider the following function:
def for_each(seq, f):
for i in seq:
f(i)
I'm sure I've seen more than one instance of someone on comp.lang.python
trying to do the equivalent of using a function such as this one to compute
the sum of the elements of a sequence as follows:
def sum(seq):
result = 0
def accum(i):
result += i
for_each(seq, accum)
return result
and wonder why it doesn't work. Still odder, why it doesn't work and the
following does:
def sum(seq):
result = [0]
def accum(i):
result[0] += i
for_each(seq, accum)
return result[0]
Transforming the first definition of sum above into the second may be
trivial, but only if you've encountered the technique before. Moreover, the
first version of sum uses a technique that is more than 45 years old (!), as
it was available to Algol 60 programmers.
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