Clojure Q&A - Recent questions tagged parsing

clojure.edn parser will not parse complete file in some cases

Wed, 07 May 2025 12:29:34 +0000

I've noticed that clojure.edn parser will skip rest of the file if it manages to find the first valid token that will complete collection. For example:

;; demo.edn
{
 :foo 1
 :bar 2 }
 :baz 3 
}

with:

(require '[clojure.edn :as edn]
         '[clojure.java.io :as io])

(with-open [r (io/reader "demo.edn")]
  (edn/read (java.io.PushbackReader. r)))

user=> {:foo 1, :bar 2}

It will also ignore rest of the file when the file is clearly malformed:

{
 :foo 1
 :bar 2 }
xxxx yyyy }}}}} {{{{ ((
 :baz 3

it returns again:

user=> {:foo 1, :bar 2}

I was expecting it to throw EOF exception or at least '}' mismatch. Is this behavior by design or a possible bug?

Support Clojure 1.12-alpha12 Array class notation

Thu, 23 May 2024 19:02:29 +0000

Currently, the function clojure.tools.reader.impl.commons/parse-symbol is fairly lax with what it allows, both in general and with regard to the forthcoming Clojure 1.12 Array class notation.

user=> (mapv trc/parse-symbol ["String/1" "String/-1" "String/11" "String/1a"])
[nil ["String" "-1"] nil nil]

This is different than the current implementation, which only accepts the first. Is there any interest in updating it to be stricter for the new notation?

Is the standard JSON parser broken ?

Mon, 18 Nov 2019 16:41:29 +0000

It seems that the "standard" json parser is happily parsing invalid json as shown below
user=> (require '[clojure.data.json :as j]) nil user=> (j/read-str "{\"a\": 123,,}") {"a" 123} user=> (j/read-str "{\"a\": 123,\"b\",}") {"a" 123}
I know other libraries exist (eg jsonista, cheshire) but it doesn't look good that what seems to be the "standard" json parser (as per the link on http://json.org/ and the fact that it lives inside the main clojure github org) is broken.

(Logged as https://clojure.atlassian.net/browse/DJSON-29)