Re: [Scheme-reports] Draft 3 Comments: Chapter 4

[Andre van Tonder <andre@x>]

On Wed, 27 Jul 2011, Denis Washington wrote:

> Thinking about it, leaving this unspecified makes sense as one couldn't
> use "when" and "unless" to return a value from a procedure anyway
> without risking an unspecified return value (if the test evaluates to #f
> or #t, respectively).
>
> On the other hand, "begin" in an expression context also a sole
> side-effect construct (otherwise, all expressions except the last in a
> "begin" form would be useless) and still returns the last expression's
> result. Given that "when" and "unless" are very similar, I find it to be
> pretty intuitive if they have the same behavior. I'm undecided.

The difference is that BEGIN in an expression context always has a last 
expression.  On the other hand, WHEN with a #f test is more like an empty 
BEGIN.

Could you maybe come up with a use case illustrating the usefulness of your 
proposed change?  I can't think of anything myself.

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