Closing the loop: An insteractive blog post made out Alex's detailed explanations: http://blog.klipse.tech/clojure/2016/11/24/stringify-clojure.html
On Mon, 21 Nov 2016 at 00:29 Alex Miller <a...@puredanger.com> wrote: > Stepping back... Clojure's print system has two families of functions - > one for human consumption and one for data. Many kinds of Clojure data > print the same in either mode (strings are one exception). > > The human printing is most commonly encountered with functions like > println, print. and str. It's designed to print things to the repl or to > the console for a person to read. Strings print without the surrounding > quotes and newlines are really printed as newlines, etc. str doesn't > directly use either Clojure printing mode but instead prints the toString() > of each object (this is Java's built-in printing system). For strings, both > Clojure's printing and str wind up just relying on Java to print a String > in a "human-readable" way. Clojure types (like maps) implement toString() > to route back into the Clojure printing system. In general, the REPL will > use data mode when printing the result of a function (this behavior can be > modified). > > The data print functions are things like pr (like print, but for data), > prn (like println, but for data), and pr-str (like str, but for data). The > idea with the data printers is that the thing you print should be readable > by Clojure. So pr-str etc will print a string as the actual characters > Clojure would need to read that string back as data. > > This is the big picture. I have left the even more complicated pretty > printing (pprint) and cl-format (following CommonLisp) parts. You are in a > maze of twisty little passages, all alike. If you look too hard at it, you > are likely to be eaten by a grue. The print and pprint systems also have > many dynamic vars to influence behavior and a number of multimethods > intended for extension or modification. In particular, you can provide your > own printers for either built-in types or custom records or types by > extending things like print-method (human) or print-dup (data). > > If anyone wanted to write a mini Clojure book, this would be a killer > topic. > > Alex > > On Sunday, November 20, 2016 at 12:30:58 PM UTC-6, Yehonathan Sharvit > wrote: > > Alex, what is the exact difference between pr-str and str (when passing a > single arg)? > > On Sun, 20 Nov 2016 at 19:40 Alex Miller <a...@puredanger.com> wrote: > > pr-str is the companion to read-string > > Although, there are many many cases where this round trip will not result > in the same input. Things like reader macros, autoresolved keywords, etc > will be expanded in the reader. > > -- > 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 a topic in the > Google Groups "Clojure" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/clojure/_qzaqqkMHHw/unsubscribe. > To unsubscribe from this group and all its topics, 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 a topic in the > Google Groups "Clojure" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/clojure/_qzaqqkMHHw/unsubscribe. > To unsubscribe from this group and all its topics, 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.
