{Time, Noop, Stream, Trap, Return}
See �transit�s English definition.
The `Transit` Context copes with the real world of finite time and computational indeterminacy.
Many algorithms require an indeterminate amount of time. Time[�] helps to negotiate the difference between a computational objective and the requirements of a finite computational resource. In 2004, a typical user assumes his or her machine has �frozen,� (presumed lost in an unproductive programming loop), if it does not manifest some degree of liveliness. Even if the computer is productively working on a task, the user will likely reboot, thereby losing whatever progress the machine may have made. Thus, any algorithm which takes considerable time must either be run on an undisturbed processor, or that algorithm must trade time with other processes to remain lively to the user. Time[�] constructions allow processes to work intermittently.
Noop copes with the fact that some computations either fail outright, or produce unintended, but anticipated results. The result of a failed process is useless. Typically, unintended algorithm results must be removed from the process stream. Noop serves this role by removing itself from its containing Sequence. Noop is also identified with error handling mechanisms and the destruction and removal of Named assignments and processes. These mechanisms help manage unintended output. By �unintended output� is meant those program branches which yield unintended results, but which are nonetheless useful.
The Stream is the essence of transit. Generally, it has an indeterminate ending. The StreamObject is a fully general abstraction that manages the minutia of files and other serial DataTypes.
Trap and Return both cope with process branching or termination. Trap & Return often manage the conjugation between processes. This is in contrast to If[�] or Branch[�] constructions, which handle local procedural branching within functions.
A Trap is often set for a result which is an alternative to the intended algorithmic result. Similarly, if some process does not produce the intended result, it is necessary to return to the framing procedure. For this purpose, Return[�] branches to a containing Head. Clearly, both Trap[�] and Return[�] have debugging applications.
transit n.
1. The action or an instance of passing or journeying across; passage through or over; as, rapid transit from city to city; the ferry makes ten transits a day; also, figuratively, transition, change; specif., a passing from this life.
In
2. Act or process of causing to pass; conveyance; carriage; as, the transit of goods through a country, or from a vendor to a purchaser. Goods shipped from one person to another are said to be in transit (cf. IN TRANSITU) from the time when delivered to the carrier by the consignor to that when actually or constructively delivered to the consignee.
3. Astrol. The passing over by another planet, after a native�s birth, the place of any planet or cusp of house in his nativity.
4. Astron. a The passage of a celestial body over the meridian of a place, or through the field of a telescope, called upper transit , or lower culmination, when below, the visible pole; --called also culmination. b The passage of a smaller body across the disk of its primary. Observations of parallax during transits of Venus have formed an important method for determining the sun�s distance, but other methods are now preferred.
transit v.
1. To make a transit across or over; as, to transit
the
transitive adj.
1. That passes on or away; transient; transitory. Now Rare.
2. Characterized by or involving transition; intermediate between one condition and another; transitional; as, a transitive state.
3. Resulting from transference of meaning; figurative. R.
4. Gram. Passing over to an object; as, a transitive action; expressing an action as not limited to the agent or subject, but directed upon an object; as, a transitive verb for or construction (he holds the book). The distinction between a transitive and an intransitive use is generally based on the presence or absence of the direct object word, since any act that involves an object (such as that of holding, killing, painting) may yet be thought of and expressed apart from any specified object (he paints well). See ABSOLUTE, adj., 6.d.
5. Law. Passing or descending (to some one), as, a transitive covenant is one which binds not only its original maker but also his representatives.
6. Math & Logic. Denoting, or characterized by, the property of passing on or being transferred successively from member to member of a class. See TRANSITIVE GROUP; TRANSITIVE RELATION.
7. Philos. a Transeunt; transient; not immanent.
Causality is transitive (not immanent) in so far as anything gives rise to effects which lie outside its own being. C.F. Stout.
b That characterize an entity (mind, self, etc.) viewed as a continuum; flowing; moving.
Urging the importance of what he (W. James) called the transitive (as
set against the more permanent substantive) parts of the stream of
consciousness.
M. Bentley.
transitive n.
Gram. A verb or construction expressive of transitive force.
transitive group. Math.
A substitution group in which each element is replaced by each other symbol by some substitution of that group. If any set of n elements is replaced by any such set, it is an n-ply transitive.
transitive relation. Logic
& Math
A relation such that if A has this relation to B, and B to C, then A has this relation to C. �Greater than,� �precedes�, �implies�, and �ancestor of�, are transitive relations.
[From Websters1949Unabridged.]
� 2004, 2005
by John Van Wie Bergamini.
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