Reference: Threading macrosλ︎
Using the threading macro, the result of every function is passed onto the next function in the list. This can be seen very clearly using ,,, to denote where the value is passed to the next function
Hint::Commas in clojure are whitespaceλ︎
Commas are simply ignored when the Clojure Reader parses code. Commas are rarely used and only to help human readability of the code
To make this really simple lets create a contrived example of the threading macro. Here we use the
str function to join strings together. Each individual
str function joins its own strings together, passing the resulting string as the first argument to the next function.
Using the thread-last macro, ->>, the result of a function is passed as the last argument of the next function call. So in another simple series of str function calls, our text comes out backwards.