control/prompt
Continuation objects
The value given to the handler in call-with-prompt, much like
the value captured by shift, is not a coroutine: it is a
continuation object. Continuation objects (or just “continuations”)
can be applied, much like functions, to continue their execution.
They may also be given to call-with-prompt.
(abort-to-prompt tag &rest)
Defined at lib/control/prompt.lisp:123:2
Abort to the prompt TAG, giving REST as arguments to the handler.
(abort/p tag &rest)
Defined at lib/control/prompt.lisp:127:2
Abort to the prompt TAG, giving REST as arguments to the handler.
(alive? k)
Defined at lib/control/prompt.lisp:159:2
Check that the continuation K may be executed further.
Example:
> (alive? (reset (shift k k)))
out = true
(block &body)
Macro defined at lib/control/prompt.lisp:177:2
Estabilish an escape continuation called break and evaluate BODY.
Example:
> (block
. (print! 1)
. (break)
. (print! 2))
1
out = nil
(call-with-escape-continuation body)
Defined at lib/control/prompt.lisp:73:2
Invoke the thunk BODY with an escape continuation.
Example
> (call-with-escape-continuation
. (lambda (return)
. (print! "this is printed")
. (return 1)
. (print! "this is not")))
this is printed
out = 1
(call-with-prompt prompt-tag body handler)
Defined at lib/control/prompt.lisp:24:2
Call the thunk BODY with a prompt PROMPT-TAG in scope. If BODY
aborts to PROMPT-TAG, then HANDLER is invoked with the coroutine
representing the rest of BODY along with any extra arguments to
abort-to-prompt.
NOTE: The given HANDLER is not executed in the scope of the
prompt, so subsequent calls to abort-to-prompt in the
continuation will not be handled.
Example
> (call-with-prompt 'tag
. (lambda ()
. (+ 1 (abort-to-prompt 'tag)))
. (lambda (k)
. (k 1)))
out = 2
(let-escape-continuation k &body)
Macro defined at lib/control/prompt.lisp:94:2
Bind K within BODY to an escape continuation.
Example
> (let-escape-continuation return
. (print! 1)
. (return 2)
. (print! 3))
1
out = 2
(let-prompt tg e h)
Macro defined at lib/control/prompt.lisp:68:2
Evaluate E in a prompt with the tag TG and handler H.
(reset &body)
Macro defined at lib/control/prompt.lisp:131:2
Establish a prompt, and evaluate BODY within that prompt.
Example
> (* 2 (reset (+ 1 (shift k (k 5)))))
out = 12
(shift k &body)
Macro defined at lib/control/prompt.lisp:146:2
Abort to the nearest reset, and evaluate BODY in a scope where
the captured continuation is bound to K.
Example
> (* 2 (reset (+ 1 (shift k (k 5)))))
out = 12
Undocumented symbols
$continuationDefined at lib/control/prompt.lisp:13:2(call/ec body)Defined at lib/control/prompt.lisp:108:1(call/p prompt-tag body handler)Defined at lib/control/prompt.lisp:66:1(continuation? continuation)Defined at lib/control/prompt.lisp:13:2(let/ec k &body)Macro defined at lib/control/prompt.lisp:109:1(let/p tg e h)Macro defined at lib/control/prompt.lisp:71:1