Well, I think you answer your own question with good reasons in the last paragraph. :)
If `acc` is an implementation detail, let's not expose it as a parameter.[1] At least, let's not do this for a function provided by a module. Especially not a function with a contract and/or documentation. But if it's a helper function that's not provided? Especially in a small module? Then I'd say it doesn't matter so much. [1]: Not even a parameter with a default value of '(), which is a 3rd possibility -- a way to try to have your cake and eat it, too. You could even have provide/contract insist that the value be '(), for "outsiders"... but inside the module the contract is N/A. I actually did this once upon a time. I changed my mind when I started to write documentation for the function, got to that parameter, and realized... yeah, nope. :) On Sat, Sep 6, 2014 at 9:55 PM, Kevin Forchione <[email protected]> wrote: > Hi guys, > Which is preferable? > > (define (foo let … (acc empty)) … (foo (rest let) ... (cons …. acc)) > > or > > (define (foo lst ...) (let loop ([lst lst] …[acc empty]) … (loop (rest let) … > (cons …. acc))) > > On the one hand we eliminate the named let construct, but on the other hand > we expose the acc in the function / contract. If the acc is not something > the caller would ever need to know about, should we hide it inside the > definition? > > -Kevin > ____________________ > Racket Users list: > http://lists.racket-lang.org/users ____________________ Racket Users list: http://lists.racket-lang.org/users
