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forth 音标拼音: [f'ɔrθ] ad. 向前方,向前 向前方,向前 forth adv 1: from a particular thing or place or position (` forth' is obsolete); " ran away from the lion"; " wanted to get away from there"; " sent the children away to boarding school"; " the teacher waved the children away from the dead animal"; " went off to school"; " they drove off"; " go forth and preach" [ synonym: { away}, { off}, { forth}] 2: forward in time or order or degree; " from that time forth"; " from the sixth century onward" [ synonym: { forth}, { forward}, { onward}] 3: out into view; " came forth from the crowd"; " put my ideas forth" n 1: a river in southern Scotland that flows eastward to the Firth of Forth [ synonym: { Forth}, { Forth River}] Forth \ Forth\, prep. Forth from; out of. [ Archaic] [ 1913 Webster] Some forth their cabins peep. -- Donne. [ 1913 Webster]
Forth \ Forth\, v.[ AS. for[ eth], fr. for akin to D. voort, G. fort [ root] 78. See { Fore}, { For}, and cf. { Afford}, { Further}, adv.] 1. Forward; onward in time, place, or order; in advance from a given point; on to end; as, from that day forth; one, two, three, and so forth. [ 1913 Webster] Lucas was Paul' s companion, at the leastway from the sixteenth of the Acts forth. -- Tyndale. [ 1913 Webster] From this time forth, I never will speak word. -- Shak. [ 1913 Webster] I repeated the Ave Maria; the inquisitor bad me say forth; I said I was taught no more. -- Strype. [ 1913 Webster] 2. Out, as from a state of concealment, retirement, confinement, nondevelopment, or the like; out into notice or view; as, the plants in spring put forth leaves. [ 1913 Webster] When winter past, and summer scarce begun, Invites them forth to labor in the sun. -- Dryden. [ 1913 Webster] 3. Beyond a ( certain) boundary; away; abroad; out. [ 1913 Webster] I have no mind of feasting forth to- night. -- Shak. [ 1913 Webster] 4. Throughly; from beginning to end. [ Obs.] -- Shak. [ 1913 Webster] { And so forth}, { Back and forth}, { From forth}. See under { And}, { Back}, and { From}. { Forth of}, { Forth from}, out of. [ Obs.] -- Shak. { To bring forth}. See under { Bring}. [ 1913 Webster]
Forth \ Forth\, n. [ OE., a ford. ? 78. See { Frith}.] A way; a passage or ford. [ Obs.] -- Todd. [ 1913 Webster] 21 Moby Thesaurus words for " forth": ahead, alee, along, away, en route to, for, forward, forwards, hence, off, on, onward, onwards, out, outward, outwardly, outwards, thence, therefrom, thereof, whence1. An interactive extensible language using
{postfix syntax} and a data stack, developed by Charles
H. Moore in the 1960s. FORTH is highly user-configurable and
there are many different implementations, the following
description is of a typical default configuration.
Forth programs are structured as lists of "words" - FORTH's
term which encompasses language keywords, primitives and
user-defined {subroutines}. Forth takes the idea of
subroutines to an extreme - nearly everything is a subroutine.
A word is any string of characters except the separator which
defaults to space. Numbers are treated specially. Words are
read one at a time from the input stream and either executed
immediately ("interpretive execution") or compiled as part of
the definition of a new word.
The sequential nature of list execution and the implicit use
of the data stack (numbers appearing in the lists are pushed
to the stack as they are encountered) imply postfix syntax.
Although postfix notation is initially difficult, experienced
users find it simple and efficient.
Words appearing in executable lists may be "{primitives}"
(simple {assembly language} operations), names of previously
compiled procedures or other special words. A procedure
definition is introduced by ":" and ended with ";" and is
compiled as it is read.
Most Forth dialects include the source language structures
BEGIN-AGAIN, BEGIN-WHILE-REPEAT, BEGIN-UNTIL, DO-LOOP, and
IF-ELSE-THEN, and others can be added by the user. These are
"compiling structures" which may only occur in a procedure
definition.
FORTH can include in-line {assembly language} between "CODE"
and "ENDCODE" or similar constructs. Forth primitives are
written entirely in {assembly language}, secondaries contain a
mixture. In fact code in-lining is the basis of compilation
in some implementations.
Once assembled, primitives are used exactly like other words.
A significant difference in behaviour can arise, however, from
the fact that primitives end with a jump to "NEXT", the entry
point of some code called the sequencer, whereas
non-primitives end with the address of the "EXIT" primitive.
The EXIT code includes the scheduler in some {multi-tasking}
systems so a process can be {deschedule}d after executing a
non-primitive, but not after a primitive.
Forth implementations differ widely. Implementation
techniques include {threaded code}, dedicated Forth
processors, {macros} at various levels, or interpreters
written in another language such as {C}. Some implementations
provide {real-time} response, user-defined data structures,
{multitasking}, {floating-point} arithmetic, and/or {virtual
memory}.
Some Forth systems support virtual memory without specific
hardware support like {MMUs}. However, Forth virtual memory
is usually only a sort of extended data space and does not
usually support executable code.
FORTH does not distinguish between {operating system} calls
and the language. Commands relating to I/O, {file systems}
and {virtual memory} are part of the same language as the
words for arithmetic, memory access, loops, IF statements, and
the user's application.
Many Forth systems provide user-declared "vocabularies" which
allow the same word to have different meanings in different
contexts. Within one vocabulary, re-defining a word causes
the previous definition to be hidden from the interpreter (and
therefore the compiler), but not from previous definitions.
FORTH was first used to guide the telescope at NRAO, Kitt
Peak. Moore considered it to be a {fourth-generation
language} but his {operating system} wouldn't let him use six
letters in a program name, so FOURTH became FORTH.
Versions include fig-FORTH, FORTH 79 and FORTH 83.
{FAQs
(http://complang.tuwien.ac.at/forth/faq/faq-general-2.html)}.
{ANS Forth standard, dpANS6
(http://taygeta.com/forth/dpans.html)}.
FORTH Interest Group, Box 1105, San Carlos CA 94070.
See also {51forth}, {F68K}, {cforth}, {E-Forth}, {FORML},
{TILE Forth}.
[Leo Brodie, "Starting Forth"].
[Leo Brodie, "Thinking Forth"].
[Jack Woehr, "Forth, the New Model"].
[R.G. Loeliger, "Threaded Interpretive Languages"].
2. {FOundation for Research and Technology - Hellas}.
(1997-04-16)
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