This specifies the variables that are initially bound in a Lisp process when that process is created. This variable is an association list of symbols and initial value forms. The initial value forms are processed by a simple evaluation that handles symbols and function call forms, but not special operators.As a special case, if the value form is the same as the symbol and that symbol is unbound, then the symbol will be unbound in the new process.
This example shows a typical use with a bound symbol:
(defvar *binding-1* 10)
(let ((mp:*process-initial-bindings*
(cons '(*binding-1* . 20)
mp:*process-initial-bindings*)))
(mp:process-run-function
"binding-1"
'()
#'(lambda (stream)
(format stream "~&Binding 1 is ~S.~%" *binding-1*))
*standard-output*)
(sleep 1))
=>
Binding 1 is 20.
This example shows the special case with an unbound symbol:
(defvar *binding-2*)
(let ((mp:*process-initial-bindings*
(cons '(*binding-2* . *binding-2*)
mp:*process-initial-bindings*)))
(flet ((check-binding-2 ()
(mp:process-run-function
"binding-2"
'()
#'(lambda (stream)
(if (boundp '*binding-2*)
(format stream "~&Binding 2 is ~S.~%" *binding-2*)
(format stream "~&Binding 2 is unbound.~%")))
*standard-output*)
(sleep 1)))
(check-binding-2)
(let ((*binding-2* 123))
(check-binding-2))))
=>
Binding 2 is unbound.
Binding 2 is 123.
LispWorks User Guide and Reference Manual - 21 Dec 2011