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Replace the some() HLDS goal with a more general scope() goal, which can be
used not just for existential quantification but also for other purposes.
The main such purposes are new goal types that allow the programmer
to annotate arbitrary goals, and not just whole procedure bodies, with the
equivalents of promise_pure/promise_semipure and promise_only_solution:
promise_pure ( <impure/semipure goal> )
promise_semipure ( <impure goal> )
promise_equivalent_solutions [OutVar1, OutVar2] (
<cc_multi/cc_nondet goal that computed OutVar1 & OutVar2>
)
Both are intended to be helpful in writing constraint solvers, as well as in
other situations.
doc/reference_manual.texi:
Document the new constructs.
library/ops.m:
Add the keywords of the new constructs to the list of operators.
Since they work similarly to the "some" operator, they have the same
precedence.
compiler/hlds_goal.m:
Replace the some(Vars, SubGoal) HLDS construct, with its optional
keep_this_commit attribute, with the new scope(Reason, SubGoal)
construct. The Reason argument may say that this scope is an
existential quantification, but it can also say that it represents
a purity promise, the introduction of a single-solution context
with promise_equivalent_solutions, or a decision by a compiler pass.
It can also say that the scope represents a set of goals that all arise
from the unraveling of a unification between a variable and a ground
term. This was intended to speed up mode checking by significantly
reducing the number of delays and wakeups, but the cost of the scopes
themselves turned out to be bigger than the gain in modechecking speed.
Update the goal_path_step type to refer to scope goals instead of just
existential quantification.
compiler/prog_data.m:
Add new function symbols to the type we use to represent goals in items
to stand for the new Mercury constructs.
compiler/prog_io_goal.m:
Add code to read in the new language constructs.
compiler/prog_io_util.m:
Add a utility predicate for use by the new code in prog_io_goal.m.
compiler/make_hlds.m:
Convert the item representation of the new constructs to the HLDS
representation.
Document how the from_ground_term scope reason would work, but do not
enable the code.
compiler/purity.m:
When checking the purity of goals, respect the new promise_pure and
promise_semipure scopes. Generate warnings if such scopes are
redundant.
compiler/det_analysis.m:
Make the insides of promise_equivalent_solutions goals single solution
contexts.
compiler/det_report.m:
Provide mechanisms for reporting inappropriate usage of
promise_equivalent_solutions goals.
compiler/instmap.m:
Add a utility predicate for use by one of the modules above.
compiler/deep_profiling.m:
Use one of the new scope reasons to prevent simplify from optimizing
away commits of goals that have been made impure, instead of the old
keep_this_commit goal feature.
compiler/modes.m:
Handle from_ground_term scopes when present; for now, they won't be
present, since make_hlds isn't creating them.
compiler/options.m:
Add two new compiler options, for use by implementors only, to allow
finer control over the amount of output one gets with --debug-modes.
(I used them when debugging the performance of the from_ground_term
scope reason.) The options are --debug-modes-minimal and
--debug-modes-verbose.
compiler/handle_options.m:
Make the options that are meaningful only in the presence of
--debug-modes imply --debug-modes, since this allows more convenient
(shorter) invocations.
compiler/mode_debug.m:
Respect the new options when deciding how much data to print
when debugging of the mode checking process is enabled.
compiler/switch_detect.m:
Rename a predicate to make it differ from another predicate by more
than just its arity.
compiler/passes_aux.m:
Bring this module up to date with our current style guidelines,
by using state variable syntax where appropriate.
compiler/*.m:
Minor changes to conform to the change in the HLDS and/or parse tree
goal type.
mdbcomp/program_representation.m:
Rename the some goal to the scope goal, and the same for path steps,
to keep them in sync with the HLDS.
browser/declarative_tree.m:
Conform to the change in goal representations.
tests/hard_coded/promise_equivalent_solutions_test.{m,exp}:
A new test case to test the handling of the
promise_equivalent_solutions construct.
tests/hard_coded/Mmakefile:
Enable the new test.
tests/hard_coded/purity/promise_pure_test.{m,exp}:
A new test case to test the handling of the promise_pure and
promise_semipure constructs.
tests/hard_coded/purity/Mmakefile:
Enable the new test.
tests/invalid/promise_equivalent_solutions.{m,err_exp}:
A new test case to test the error messages for improper use of the
promise_pure and promise_semipure constructs.
tests/invalid/Mmakefile:
Enable the new test.
46 lines
1.0 KiB
Mathematica
46 lines
1.0 KiB
Mathematica
% Various checks that promise_equivalent_solutions goals are treated properly.
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:- module promise_equivalent_solutions_test.
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:- interface.
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:- import_module io.
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:- pred main(io::di, io::uo) is det.
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:- implementation.
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:- import_module int, list, string.
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main(!IO) :-
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% The equality theory with respect to which all solutions of the goal
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% inside the promise_equivalent_solutions are equivalent is the one
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% that views the lists as unsorted representations of sets, possibly
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% with duplicates.
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promise_equivalent_solutions [B] (
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( A = [1, 2]
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; A = [2, 1]
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),
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( B = [44, 33]
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; B = [33, 44]
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)
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),
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list__sort_and_remove_dups(A, ASorted),
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list__sort_and_remove_dups(B, BSorted),
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io__write(ASorted, !IO),
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io__nl(!IO),
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io__write(BSorted, !IO),
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io__nl(!IO),
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(
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promise_equivalent_solutions [C, ASorted] (
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ASorted = [_ | ATail],
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( C = [5] ++ ATail
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; C = ATail ++ [5]
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)
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)
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->
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list__sort_and_remove_dups(C, CSorted),
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io__write(CSorted, !IO),
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io__nl(!IO)
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;
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io__write("cannot compute CSorted\n", !IO)
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).
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