An alternative that would permit you to manipulate your facts 
in a somewhat second-order manner is to define a predicate such as my-fact
and then use:
    (assert (my-fact ?foo ?bar))

This way, ?foo is no longer a predicate but instead is a term within the fact 
  ----- Original Message ----- 
  From: Friedman-Hill, Ernest 
  To: jess-users 
  Sent: Monday, April 16, 2012 10:27 AM
  Subject: Re: JESS: [EXTERNAL] Second order JESS?

  You can build the fact you want as a string and assert that — for example

  (assert-string (str-cat "(" ?foo " " ?bar ")"))

  From: Sam Sarjant <>
  Reply-To: <>
  Date: Sun, 15 Apr 2012 13:21:47 +1200
  To: <>
  Subject: JESS: [EXTERNAL] Second order JESS?

    I'm looking to use JESS within an application where second-order logic is 
needed (or at least it makes things easier). Does JESS support second-order 
logic in any form?

  For example, a rule such as:
  (ruleDef (factPredicate ?foo) (factArgs ?bar))
  (assert (?foo ?bar)))

  is an example of the structure I am looking for (where factPredicate is a 
String slot and factArgs is a multislot). The LHS of the rule compiles fine 
(with the appropriate ruleDef deftemplate), but the RHS throws an exception as 
it is expecting a template name after assert.

  - Thanks, Sam Sarjant

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