Actions
enact Y
- enact Y:a reflective action, where Y is a
yielder of abstractions. Represents performing an action in a context
different from that of its occurrence.
- Performs the action incorporated in the abstraction yielded by
evaluating Y.
- The performance of the incorporated action is given no
data. (But see the abstraction yielder application d1
to d2.)
- The performance of the incorporated action receives no bindings.
(But see the abstraction yielder closure d.)
Actions| Yielders| Data
- Performs the action incorporated in the abstraction yielded by
evaluating Y.
Yielders
application d1 to d2 | closure d
- application d1 to d2: an abstraction, when d1 is
an abstraction and d2 is data. Incorporates the same action as d1,
except that the incorporated action is given d2 as transients whenever the
abstraction is enacted. Represents supplying transients to an
abstraction (precluding the supply of further transients).
This operation extends to yielders Y1, Y2 in the usual way: it is evaluated by applying the above operation to the data yielded by evaluating Y1, Y2.
- closure d:an abstraction yielder, where d is an abstraction. Yields an abstraction which incorporates the same action as d, except that the incorporated action receives particular bindings whenever the abstraction is enacted. The bindings are those current for the evaluation of closure d.
This operation extends to yielders Y in the usual way: it is evaluated by applying the above operation to the datum yielded by evaluating Y.
The yielder closure abstraction of A represents reification of an action as an abstraction with static bindings. The action enact the closure of a given abstraction represents reflection of an abstraction with dynamic bindings (unless static bindings were already supplied to it). The action enact a given abstraction represents reflection of an abstraction with no bindings (unless static bindings were already supplied to it).
Actions| Yielders| Data
- closure d:an abstraction yielder, where d is an abstraction. Yields an abstraction which incorporates the same action as d, except that the incorporated action receives particular bindings whenever the abstraction is enacted. The bindings are those current for the evaluation of closure d.
Data
abstraction | abstraction of A | provision d | production d
- abstraction: the sort of datum that incorporates (i.e.,
reifies) an action. The incorporated action is performed when the
abstraction is enacted (i.e., reflected).
- abstraction of A: an abstraction, where A is an action. Incorporates A. Represents (a pointer to) the `code' implementing A. Yielders occurring in A do not get evaluated when the abstraction is evaluated: they are left for evaluation during the performance of the incorporated action.
- Every action-operation (i.e., operation specified for arguments included in action) is extended to arguments of sort abstraction, and thus to yielder. For example, if a1 and a2 are abstractions that incorporate actions A1 and A2 respectively, a1 and then a2 is the abstraction that incorporates the action A1 and then A2.
- provision d: an abstraction, where d is data. Incorporates the action give d. Useful when the argument is a yielder of data. For example, an evaluation of provision given data yields an abstraction which, when enacted, always gives the same data, namely that given to the evaluation.
- production d: an abstraction, where d is bindings or redirections. Incorporates the action produce d. Useful when the argument is a yielder of bindings. For example, an evaluation of production current bindings yields an abstraction which, when enacted, always reflects the bindings received by the evaluation.
Actions| Yielders| Data
- abstraction of A: an abstraction, where A is an action. Incorporates A. Represents (a pointer to) the `code' implementing A. Yielders occurring in A do not get evaluated when the abstraction is evaluated: they are left for evaluation during the performance of the incorporated action.
[Created by Jin Jin Yi and Ana Carla Santos. Last modified at 21 Dec 1997 by Ana Carla]