Aside from the vector syntax, Data::SExpression also currently cannot handle the unquoted @ symbol: 

(@ . [(20181225 1438) ((emacs (24 3))) "multiple-inheritance prototype
+-based objects DSL" tar ((:commit . "0a6189f8be42dbbc5d9358cbd447d471
+236135a2") (:authors ("Christopher Wellons" . "wellons@nullprogram.co
+m")) (:maintainer "Christopher Wellons" . "wellons@nullprogram.com") 
+(:url . "https://github.com/skeeto/at-el"))])

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By replacing with ( ) and @ with "@", the data parses.

2020-04-09 Athanasius fixed formatting of over-long code line.

In reply to Re^2: Parsing Emacs Lisp sexpr? by perlancar
in thread Parsing Emacs Lisp sexpr? by perlancar

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