81 thread

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     % vim: ft=mercury ts=4 sw=4 et
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     % Copyright (C) 2000-2001,2003-2004, 2006-2008, 2010-2011 The University of Melbourne.
     % This file may only be copied under the terms of the GNU Library General
     % Public License - see the file COPYING.LIB in the Mercury distribution.
     %--------------------------------------------------%
     %
     % File: thread.m.
     % Main author: conway.
     % Stability: medium.
     %
     % This module defines the Mercury concurrency interface.
     %
     % The term `concurrency' here refers to threads, not necessarily to parallel
     % execution.  (The latter is also possible if you are using one of the .par
     % grades and the lowlevel C backend, e.g. grade asm_fast.par.gc).
     %
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     :- module thread.
     :- interface.
     
     :- import_module io.
     
     :- include_module channel.
     :- include_module mvar.
     :- include_module semaphore.
     
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         % can_spawn succeeds if spawn/3 is supported in the current grade.
         %
     :- pred can_spawn is semidet.
     
         % spawn(Closure, IO0, IO) is true iff `IO0' denotes a list of I/O
         % transactions that is an interleaving of those performed by `Closure'
         % and those contained in `IO' - the list of transactions performed by
         % the continuation of spawn/3.
         %
     :- pred spawn(pred(io, io)::in(pred(di, uo) is cc_multi),
         io::di, io::uo) is cc_multi.
     
         % yield(IO0, IO) is logically equivalent to (IO = IO0) but
         % operationally, yields the Mercury engine to some other thread
         % if one exists.
         %
         % NOTE: this is not yet implemented in the hl*.par.gc grades; currently
         % it is a no-op in those grades.
         %
     :- pred yield(io::di, io::uo) is det.
     
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