A library for rearranging filter map join, etc. Clojure style

Questions & Answers
1

Hi,

I've seen a Racket library which allows for structuring filtering and mapping Clojure style, like this:

  (->> (-> (cs/replace authors #"\"(?:\\.|[^\"\\])*\"" " ")  ;; Remove quoted substrings.
           (cs/replace #"\"" " ")  ;; Remove odd quotes.
           (cs/split #","))
       (filter (fn [author]
                 (-> (cs/replace author #"[-.]+" "")
                     (cs/blank?)
                     (not))))
       (map (fn [author] (as-> (cs/split author #"-") b
...

So far as I can remember, even ->> was there. I can't find anything, though.

2

You're probably thinking of threading.

3

In addition to threading, there’s also Qi and at least one “Racket like it’s Clojure” package. I recommend searching the docs for -> and ~> and seeing possibilities come up.

4

Yes, it's about threading (?), and the keyword that stuck in my memory is ~>>, not ->>, from Qi :blush: .

Why are there so many almost identical libraries?

5

Just in case I wasn't clear, I mean there's a racket library named threading. I can't tell if you're saying it's about threading (the concept) or the library by that name.

6

I'm not sure about the terminology. It looks like threading and qi do much the same thing.

7

Qi builds on threading (at least conceptually) but offers quite a bit more. For example: (define-flow avg (~> (-< + count) /)) defines a variadic avg that computes the average of it’s numerical inputs.

8

The threading library mentioned above has a simplified version called "create threading in 2 easy steps",

https://lexi-lambda.github.io/racket-macro-exercises/index.html