Re: [Haskell-cafe] Mutual scoping question

It seems (surprisingly to me) that such pattern matches are allowed at the top level, so that would simplify my kludge a bit by skipping the definition of fg. But is using pairs (or the equivalent) in this way the only solution? I was hoping that there might be some kind of top-level definition syntax like {f .. = ... ; g .. = ...} where h .. = ... that would correctly capture the scoping I'm looking for. --Todd On Wed, Nov 22, 2023 at 5:43 PM Jeff Clites wrote:

Can you do:

(f, g) = let f’ = … in (f’, g’)

or is a pattern match not allowed at top level?

Jeff

On Nov 22, 2023, at 4:40 PM, Todd Wilson wrote:

 Hello, Cafe:

Is there a preferred way to define two top-level mutually recursive functions, f and g, that both use a common local function h such that h is (1) only defined once and (2) does not escape the scope of f and g? I suppose it could be done like this:

fg = let f ... = ... f,g,h ... g ... = ... f,g,h ... h ... = ... h ... in (f,g) f = fst fg g = snd fg

but is there something more elegant than this that I'm not seeing?

Todd Wilson _______________________________________________ Haskell-Cafe mailing list To (un)subscribe, modify options or view archives go to: http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe Only members subscribed via the mailman list are allowed to post.