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https://github.com/Mercury-Language/mercury.git
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6d88f700a7
Estimated hours taken: 1.5 Fix a couple of bugs related to pruning of impure goals with no output variables. compiler/det_analysis.m: Fix a bug: the compiler was automatically inserting pruning across impure goals with no output variables. That should happen only for pure or semipure goals. To prevent pruning in those cases, I changed it so that impure goals with no output variables are not considered single-solution contexts. doc/reference_manual.texi: Document the above-mentioned change. compiler/clause_to_proc.m: Fix a bug: when converting a bunch of clauses into a disjunction, clause_to_proc.m was not computing the proper purity annotation on the goal_info for the disjunction. tests/hard_coded/Mmakefile: tests/hard_coded/impure_prune.m: tests/hard_coded/impure_prune.exp: A test case for the above-mentioned changes to det_analysis.m and clause_to_proc.m.
41 lines
946 B
Mathematica
41 lines
946 B
Mathematica
:- module impure_prune.
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:- interface.
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:- import_module io.
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:- pred main(state::di, state::uo) is det.
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:- implementation.
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:- import_module int, require.
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:- pragma promise_pure(main/2).
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main -->
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( { impure do_impure_stuff, fail } ->
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{ error("not reached") }
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;
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{ semipure get_counter(X) },
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print("X = "), print(X), nl
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).
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:- impure pred do_impure_stuff is multi.
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do_impure_stuff :-
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impure bump_counter.
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do_impure_stuff :-
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impure bump_counter.
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do_impure_stuff :-
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impure bump_counter.
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:- impure pred bump_counter is det.
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bump_counter :-
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semipure get_counter(X),
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impure set_counter(X + 1).
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:- semipure pred get_counter(int::out) is det.
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:- impure pred set_counter(int::in) is det.
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:- pragma c_header_code("extern Integer counter;").
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:- pragma c_code("Integer counter = 0;").
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:- pragma c_code(get_counter(X::out), will_not_call_mercury, "X = counter;").
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:- pragma c_code(set_counter(X::in), will_not_call_mercury, "counter = X;").
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