On 22 Jan 2013, at 11:28, Олег wrote:

(json:with-decoder-simple-clos-semantics (let ((json:*json-symbols-package* nil)) (let ((x (json:decode-json-from-string "{\"foo1\": [1, 2, 3], \"bar1\": true, \"baz1\": \"!\"}"))) (with-slots (foo1 bar1 baz1) x (values x foo1 bar1 baz1)))))

The slot FOO1 is unbound in the object #<#<JSON:FLUID-CLASS NIL {1004085F33}> {1003CAFB43}>. [Condition of type UNBOUND-SLOT]

When Lisp slot names are derived from JSON object keys, they are transcribed to more Lisp-like conventions: camel case is replaced with hyphenation, all caps become framing asterisks, etc. So, slot names in your Lisp code should be written with hyphens: (json:with-decoder-simple-clos-semantics (let ((json:*json-symbols-package* nil)) (let ((x (json:decode-json-from-string "{\"foo1\": [1, 2, 3], \"bar1\": true, \"baz1\": \"!\"}"))) (with-slots (foo-1 bar-1 baz-1) x (values x foo-1 bar-1 baz-1))))) => #<#<JSON:FLUID-CLASS NIL {5D03A341}> {5A1ECF11}> => #(1 2 3) => T =>"!" If this disagrees too much with the conventions of your code, you can change the way identifiers are transcribed by setting / rebinding the variable *JSON-IDENTIFIER-NAME-TO-LISP* to the appropriate transcriber function. Hope this helps. — B. Smilga.