[LOGIC-38] Logic Threading Macro

Sun, 13 May 2012 11:19:08 -0500

This macro was somewhat useful when I was implementing static analysis for a compiler with core.logic.

(defmacro ==>> [expr-in & rel-forms]
"Thread the expr-in through rel-forms then unify with last rel-forms
(the 'out expression').

Example:
(==>> [[1]] (firsto) (firsto) x))
;; 'x' will become bound to value 1

This macro expands to:
(fresh [_A _B]
(firsto [[1]] _A)
(firsto _A _B)
(== _B q))

If you imagine that the 'return value' of firsto is its last parameter,
then it works just like clojure.core/-> as return value of each form is
first argument of the following form."

Clojure JIRA

[LOGIC-38] Logic Threading Macro