This is very cool. You might take a look at the `threading` module for additional ideas: https://docs.racket-lang.org/threading/index.html
On Tue, Mar 9, 2021 at 10:20 AM Roger Keays <rac...@rogerkeays.com> wrote: > Hi all, > > I recently publish a new package called *fluent* which adds some syntax > enhancements to Racket. Links and README below. Let me know what you > think... > > Roger > > https://pkgs.racket-lang.org/package/fluent > https://github.com/rogerkeays/racket-fluent/ > > # fluent > > UNIX style pipes and a lambda shorthand syntax to make your Racket code > more readable. > > ## ? Unpopular So LISP Is Why > > Let's be honest. LISP missed a huge opportunity to change the world by > telling developers they have to think backwards. Meanwhile, UNIX became > successful largely because it allows you to compose programs sequentially > using pipes. Compare the difference (the LISP example is actually racket): > > UNIX: cat data.txt | grep "active" | cut -f 4 | uniq | sort > LISP: (sort (remove-duplicates (map (λ (line) (list-ref (string-split > line) 4)) ((filter (λ (line) (string-contains? line "active")) (file->lines > "data.txt")))))) > > Using *fluent*, the same racket code can be written according to the UNIX > philosophy: > > ("data.txt" > file->lines >> filter (line : line > string-contains? > "active") >> map (line : line > string-split > list-ref 4) > > remove-duplicates > sort) > > You can use unicode → instead of > if you prefer. It is more distinctive > and a bit easier on the eyes: > > ("data.txt" → file->lines →→ filter (line : line → string-contains? > "active") →→ map (line : line → string-split → list-ref 4) → > remove-duplicates → sort) > > ## Function Composition > > Using the function composition operator (> or →), *fluent* inserts the > left hand side as the first parameter to the procedure on the right hand > side. Use >> (or →→) to add the left hand side as the last parameter to the > procedure. > > (data > procedure params) becomes (procedure data params) > (data >> procedure params) becomes (procedure params data) > > This operation can be chained or nested as demonstrated in the examples. > > ## Lambda Shorthand > > The : operator allows you to easily write a lambda function with one > expression. Parameters go on the left, the expression on the right, no > parentheses required. For example: > > > ((x : + x 1) 1) > 2 > > ((x y : + x y) 1 2) > 3 > > (map (x : string-upcase x) '("a" "b" "c")) > '("A" "B" "C") > > ## Math Procedures > > Since this library uses > for function composition, the built in > greater-than procedure is renamed to `gt?`. Note, this could break existing > code if you are already using the > procedure. Other math procedures are > also renamed for consistency, and because the text versions read more > naturally when using function composition. > > > gt? > < lt? > >= gte? > <= lte? > + add > - subtract > * multiply > / divide > > ## Convenience Procedures > > *fluent* works best when the data (input) parameter comes first. Most > racket functions do this out of the box, but many functions which take a > procedure as a parameter put the data last. That's fine, because you can > just use >>. Alternatively you can wrap and rename the procedure, which is > what we've done for these functions: > > original data-first version > ----------------------------- > for-each iterate > > example: > > > ('(1 2 3) → iterate (x : displayln x)) > 1 > 2 > 3 > > ## Comparison to Clojure's Threading Macro > > Clojure's threading macro is a prefix operator, which means it is less > readable when nested and requires more parentheses. You could say that the > *fluent* infix operator acts as one parenthesis. Compare: > > CLOJURE (prefix): > > (-> (list (-> (-> id3 (hash-ref 'genre "unknown")) normalise-field) > (-> (-> id3 (hash-ref 'track "0")) normalise-field) > (-> (-> id3 (hash-ref 'artist "unknown")) normalise-field) > (-> (-> id3 (hash-ref 'title "unknown")) normalise-field)) > (string-join ".")) > > FLUENT (infix): > > (list (id3 → hash-ref 'genre "unknown" → normalise-field) > (id3 → hash-ref 'track "0" → normalise-field) > (id3 → hash-ref 'artist "unknown" → normalise-field) > (id3 → hash-ref 'title "unknown" → normalise-field)) → > string-join ".") > > Fluent's infix approach also makes it easier to combine thread-first (→) > with thread-last (→→). > > ## How to enter → with your keyboard > > → is Unicode character 2192. On linux you can enter this using > `shift-ctrl-u 2192 enter`. Naturally, if you want to use this character, > you should map it to some unused key on your keyboard. This can be done > with xmodmap: > > # use xev to get the keycode > $ xev > > # check the current mapping > $ xmodmap -pke > > # replace the mapping > $ xmodmap -e "keycode 51=U2192 Ccedilla ccedilla Ccedilla braceright > breve braceright" > > Making this change permanent depends on your session manager. Search > duckduckgo for details. > > ## Installation > > This library is available from the Racket package collection and can be > installed with raco: > > $ raco pkg install fluent > > All you need to do is `(require fluent)`. You can try it out in the REPL: > > > (require fluent) > > ("FOO" > string-downcase) > "foo" > > ((x y : x > add y) 1 2) > 3 > > -- > You received this message because you are subscribed to the Google Groups > "Racket Users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to racket-users+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/racket-users/sigid.1702887e81.20210309152029.GA3105%40papaya.papaya > . > -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/racket-users/CAE8gKod-vE2H2bS%3DJGmVc%3DQa-CmrsZYvfbx1cJsoLWRhfVKfww%40mail.gmail.com.
