santiagocabrera96

santiagocabrera96

Programming Clojure, Fourth Edition: clojure.core/read note is not clear. (page 50)

Hi!

In page 50 of the book, chapter 3. In the clojure.core/read section it has the following text:

One important note is that the read functions read the “next” value from the character stream or string and leave or ignore any value after that. The read and read-string functions have special options that allow you to ensure the input is fully read if needed.

I don’t understand what that means. My understanding initially reading this was that it is possible to read all the values present in the string/stream, but checking the documentation I don’t see this.

Reading the doc of read.

(doc read)
-------------------------
clojure.core/read
([] [stream] [stream eof-error? eof-value] [stream eof-error? eof-value recursive?] [opts stream])
  Reads the next object from stream, which must be an instance of
  java.io.PushbackReader or some derivee.  stream defaults to the
  current value of *in*.

  Opts is a persistent map with valid keys:
    :read-cond - :allow to process reader conditionals, or
                 :preserve to keep all branches
    :features - persistent set of feature keywords for reader conditionals
    :eof - on eof, return value unless :eofthrow, then throw.
           if not specified, will throw

  Note that read can execute code (controlled by *read-eval*),
  and as such should be used only with trusted sources.

  For data structure interop use clojure.edn/read
 

I guessed is what recursive? does, but trying it out doesn’t seem to be the case.

Can someone help me understand this section please?

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