conditionals in lambdas?

[Steve Horne]

I agree with most of what you say, and I confess I wasn't thinking of
it. Also, I have no idea why I suddenly thought list subscripts
started at 1.

However, did you realise how easy a lazy version is to create...

Using tuples (which do seem clearer than my list version, and probably
better in other ways to)...

  (no_value,yes_value) [condition]

This can be adapted as follows...

  ((lambda : no_value, lambda : yes_value) [condition]) ()

That is, the indexing operation selects which lambda to evaluate.

Of course the lambdas may need some default parameters, and could
easily get a bit awkward syntactically. But it should work.

So with the case using division...

  ((lambda : 0, lambda j=j : 1/j) [j != 0]) ()

-- 
Steve Horne
sh at ttsoftware.co.uk