[plt-scheme] to define, or to let

Bradd W. Szonye wrote:
> Paul Schlie wrote:
> > Felix, Thanks for the clarification, however regardless of the
> > "belief" that a programmer may have with respect to the relative
> > independence of a collection of expressions, they may none the less
> > actually have potentially subtle interdependencies which may not
> > clearly express themselves until executed within an environment which
> > chooses to evaluate them in a different order ....
>
> That's hardly unique to this feature.

Right.  For example, you could make the exact same argument for static
typechecking:

"Regardless of the 'belief' that a programmer may have with respect to the
types of expressions, they may none the less actually have potentially
subtly different types which may not clearly express themselves until
executed with a particular set of inputs ... which will result in an
otherwise needless unanticipated failure."

PLT Scheme experiences such a "needless" unanticipated failure every time it
produces a runtime type error.  Languages and programs that are not
statically typed have various disturbing semantic properties of their own,
but some of us like to put up with those, because we care more about the
other side of the tradeoff, to the point where we're willing to take a risk
that we know can be entirely eliminated, at a cost.

We're just arguing about its cost vs. its worth, and that's entirely
subjective and probably even domain-dependent.

Anton