These are all just sugar over monadic bind, right? Here's one way to do it in the ocaml alternate universe: https://github.com/janestreet/ppx_let#syntactic-forms-and-actual-rewriting
But it can be made to work for async or options or whatever, too. We can put the async helpers in the same bucket: https://github.com/ztellman/manifold/blob/master/docs/deferred.md#let-flow The general idea is turning function application into something that looks less nested. On Wed, Oct 3, 2018 at 10:22 PM Mark Engelberg <mark.engelb...@gmail.com> wrote: > This looks like a case of "convergent evolution". > > Having the ability to do a :let in the middle of a cond feels like one of > those things that *should* be in the core language, so if it's not in > there, a bunch of people are naturally going to arrive at the same solution > and make it happen in their own utility libraries. A bunch of us Clojure > programmers from the early 1.0 days had been privately passing around and > using a "cond that supports :let bindings" macro for years. The first time > I saw the macro was in a blog post by Christophe Grand. I really hoped it > would make it into Clojure proper -- other functional languages like Racket > and F# support ways to bind local variables with "clearer, more linear > code, that doesn't make a march for the right margin", as Howard Lewis Ship > put it. But after several years had passed without any indication that > CLJ-200 was ever going to be addressed, I eventually made the improved cond > macro into a clojars library. > > walmartlabs' cond-let addresses the most important thing (let), which is > the critical piece of functionality that feels like the most natural, > needed addition to the language. better-cond's :let syntax is identical. > But as us old-school Clojurians passed around the "better cond" macro over > the years, it grew in functionality. So in better-cond, I included the > other little improvements that had accumulated over time, which I had found > useful. So better-cond also supports :when, :when-let, and :do (and will > soon have :when-some). :let is the only piece that I felt really belonged > in the core language's cond, and if CLJ-200 had made it into the core > language, I would have been content to just use Clojure's own cond. But > once I realized I was going to need a library to achieve the much-needed > :let inside of cond, I figured I might as well use that library to include > the other convenient cond additions as well. So better-cond is a superset > of cond-let's functionality, with support for :let plus a few bonuses. > > Use whichever one strikes your fancy. cond-let is perfect if all you care > about is adding :let to your cond. If you want to experiment with some of > the other features beyond :let, you could use better-cond and see what you > think. > > Either way, I strongly encourage you to use one of these two libraries so > you can start using :let inside your cond. I agree fully with Howard Lewis > Ship that it results in clearer code. Try either library which supports > this -- it will change your life! > > > On Wed, Oct 3, 2018 at 5:05 PM Matching Socks <phill.w...@gmail.com> > wrote: > >> Is this a refinement of Mark Engelberg's "better-cond", or an alternative >> approach? >> >> I have not used better-cond myself, but it starts here: >> https://dev.clojure.org/jira/browse/CLJ-200. >> >> -- >> You received this message because you are subscribed to the Google >> Groups "Clojure" group. >> To post to this group, send email to clojure@googlegroups.com >> Note that posts from new members are moderated - please be patient with >> your first post. >> To unsubscribe from this group, send email to >> clojure+unsubscr...@googlegroups.com >> For more options, visit this group at >> http://groups.google.com/group/clojure?hl=en >> --- >> You received this message because you are subscribed to the Google Groups >> "Clojure" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to clojure+unsubscr...@googlegroups.com. >> For more options, visit https://groups.google.com/d/optout. >> > -- > You received this message because you are subscribed to the Google > Groups "Clojure" group. > To post to this group, send email to clojure@googlegroups.com > Note that posts from new members are moderated - please be patient with > your first post. > To unsubscribe from this group, send email to > clojure+unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/clojure?hl=en > --- > You received this message because you are subscribed to the Google Groups > "Clojure" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to clojure+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Clojure" group. 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