We have removed is as a synonym for unification.
We have reserved =</2 as a type name.
A term with a top-level functor coerce/1 is now treated as a type conversion expression. To call a function named coerce/1, you can module qualify the name at the call site, or wrap parentheses around the name, e.g. (coerce)(Arg).
We have renamed the lexer and parser modules of the Mercury standard library to mercury_term_lexer and mercury_term_parser respectively.
We have made slight changes to the names and/or the functionality of several predicates in the getopt and getopt_io modules.
We have removed the legacy support for the Alpha architecture.
We have dropped support for macOS 10.8 and earlier.
We have removed the Erlang backend as it was unmaintained.
random.system_rngarray moduleThe following obsolete predicates and functions have been removed:
bsearch/3 (replacement: binary_search/3)bsearch/4 (replacement: binary_search/4)least_index/1 (replacement: min/1)greatest_index/1 (replacement: max/1)The following predicate has been added:
generate_foldl2/7array2d moduleThe following predicates and functions have been added:
lookup/3 (synonym for Array ^ elem(R, C))lookup/4 (synonym for Array ^ elem(R, C))unsafe_lookup/3 (synonym for Array ^ unsafe_elem(R, C))unsafe_lookup/4 (synonym for Array ^ unsafe_elem(R, C))The lists/1 function now returns an empty list for a 0x0 array.
assoc_list moduleThe following predicate has been added:
maybe_from_corresponding_lists/3bag moduleThe following obsolete predicates and functions have been removed:
to_set_without_duplicates/1 (replacement: func to_set/1)to_set_without_duplicates/2 (replacement: func to_set/1)bitmap moduleThe following predicates and functions have been added:
get_bit/2get_bits/2get_byte/2set_bit/4set_bit/4set_byte/4unsafe_get_bit/2unsafe_get_bits/2unsafe_get_byte/2unsafe_set_bit/4unsafe_set_bits/4unsafe_set_byte/4char moduleThe following predicates have been added:
unsafe_base_digit_to_int/3to_utf8_uint8/2to_utf16_uint16/2The following obsolete predicates and functions have been removed:
det_int_to_digit/1 (replacement: det_int_to_decimal_digit/1)det_int_to_digit/2 (replacement: det_int_to_decimal_digit/2)digit_to_int/2 (replacement: decimal_digit_to_int/2)int_to_digit/2 (replacement: int_to_decimal_digit/2)cord moduleThe following predicates have been added:
foldl2/6foldl3/8dir moduleThe following predicate has been added:
general_foldl2/8getopt moduleThe following new predicates have been added:
The following variants of the existing process_options predicate have been added:
process_options_io/6process_options_io/7process_options_track_io/9process_options_userdata/8process_options_userdata_io/10The ones whose names have an _io suffix do the same jobs as the corresponding predicates without the _io suffix, with the exception that they also have a pair of I/O state arguments that allow them to implement file_special options. This functionality used to be available only from the getopt_io module.
The following predicates have had their argument types changed:
process_options/6process_options/7process_options_track/7All these predicates used to return error indications in the form of a simple string. They now return error indications using the existing structured type option_error, which can be converted into a string on demand.
The following predicates have been deleted:
process_options_se/6process_options_se/7process_options_track_se/7Their functionality is now available from the predicates with the same name minus the _se suffix.
getopt_io modulegetopt module, but it is scheduled to be deleted after the next release.int moduleThe following functions have been added:
uint_to_lc_hex_string/2 (synonym for uint_to_hex_string/2)uint64_to_lc_hex_string/2 (synonym for uint64_to_hex_string/2)The following obsolete predicates and functions have been removed:
is/2 (replacement: =, i.e. unification)legacy_left_shift/2 (replacement: <<)legacy_right_shift/2 (replacement: >>)int32 moduleThe following functions have been added:
cast_to_int8cast_from_int8cast_to_int16cast_from_int16cast_to_int64cast_from_int64integer moduleThe following obsolete functions have been removed:
from_base_string/2 (replacement: pred from_base_string/3)from_string/2 (replacement: pred from_string/2)int/2 (replacement: det_to_int/1)io moduleThe following predicates have been added to this module:
get_environment_var_map/3read_binary_int8_unboxed/5read_binary_uint8_unboxed/5read_named_file_as_string/4read_named_file_as_lines/4write_line_cc/4The following obsolete predicates have been removed:
make_temp/3 (replacement: make_temp_file/3)make_temp/5 (replacement: make_temp_file/5)The following predicates have been marked as obsolete:
see/4 (replacement: prolog.see/4)see_binary/4 (replacement: prolog.see_binary/4)seen/2 (replacement: prolog.seen/2)seen_binary/2 (replacement: prolog.seen_binary/2)tell/4 (replacement: prolog.tell/4)tell_binary/4 (replacement: prolog.tell_binary/4)told/2 (replacement: prolog.told/2)told_binary/2 (replacement: prolog.told_binary/2)The following predicate has been renamed:
report_stats/2 to report_standard_stats/2.lexer modulemercury_term_lexer, to make name clashes between it and user-written modules less likely.list moduleThe following predicates have been added:
delete_nth/3foldl7/16foldl8/18foldl4_corresponding/11The following obsolete predicate has been removed:
takewhile/4 (replacement: take_while/4)map moduleThe following predicates have been added to this module:
foldl6/14foldl6_values/14foldr6/14maybe moduleThe following predicates have been added to this module:
foldl3_maybe/8foldl4_maybe/10foldl5_maybe/12map_foldl4_maybe/11map_foldl5_maybe/13parser modulemercury_term_parser, to make name clashes between it and user-written modules less likely.prolog moduleThe following predicate has been added to this module:
is/2 (moved here from the int module)see/4 (moved here from the io module)see_binary/4 (moved here from the io module)seen/2 (moved here from the io module)seen_binary/2 (moved here from the io module)tell/4 (moved here from the io module)tell_binary/4 (moved here from the io module)told/2 (moved here from the io module)told_binary/2 (moved here from the io module)random moduleThe following obsolete predicate has been removed:
test/4 (replacement: none)std_util moduleThe following obsolete predicates and functions have been removed:
maybe_func/2 (replacement: func maybe.func_to_maybe/1)maybe_pred/3 (replacement: func maybe.pred_to_maybe/1)string moduleThe following functions have been added:
add_suffix/2split_into_lines/1to_uint/2det_to_uint/1base_string_to_uint/3det_base_string_to_uint/2uint_to_hex_string/1uint_to_uc_hex_string/1uint_to_octal_string/1uint64_to_hex_string/1uint64_to_uc_hex_string/1uint64_to_octal_string/1The following function symbols have been added to the type poly_type:
i8(int8)i16(int16)i32(int32)i64(int64)u8(uint8)u16(uint16)u32(uint32)u64(uint64)This allows predicates such as string.format and io.format to operate on values of not just the word sized integer types int and uint, but on sized versions of them as well.
term moduleThe following obsolete predicates and functions have been removed:
func var_id/1 (replacement: var_to_int/1)
relabel_variable/3 (replacement: rename_var_in_term/4)relabel_variable/4 (replacement: rename_var_in_term/4)relabel_variables/3 (replacement: rename_var_in_terms/4)pred relabel_variables/4 (replacement: rename_var_in_terms/4)
rename/3 (replacement: rename_var_in_term/4)rename/4 (replacement: rename_var_in_term/4)rename_list/3 (replacement: rename_var_in_terms/4)pred rename_list/4 (replacement: rename_var_in_terms/4)
apply_renaming/3 (replacement: apply_renaming_in_term/3)apply_renaming/3 (replacement: apply_renaming_in_term/3)apply_renaming_to_list/3 (replacement: apply_renaming_in_terms/3)pred apply_renaming_to_list/3 (replacement: apply_renaming_in_terms/3)
apply_variable_renaming/2 (replacement: apply_renaming_in_term/3)apply_variable_renaming/3 (replacement: apply_renaming_in_term/3)apply_variable_renaming_to_list/2 (replacement: apply_renaming_in_terms/3)pred apply_variable_renaming_to_list/3 (replacement: apply_renaming_in_terms/3)
apply_variable_renaming_to_var/2 (replacement: apply_renaming_in_var/3)apply_variable_renaming_to_var/3 (replacement: apply_renaming_in_var/3)apply_variable_renaming_to_vars/2 (replacement: apply_renaming_in_vars/3)pred apply_variable_renaming_to_vars/3 (replacement: apply_renaming_in_vars/3)
substitute/3 (replacement: substitute_var_in_term/4)substitute/4 (replacement: substitute_var_in_term/4)substitute_list/3 (replacement: substitute_var_in_terms/4)pred substitute_list/4 (replacement: substitute_var_in_terms/4)
substitute_corresponding/3 (replacement: substitute_corresponding_in_term/4)substitute_corresponding/4 (replacement: substitute_corresponding_in_term/4)substitute_corresponding_list/3 (replacement: substitute_corresponding_in_terms/4)pred substitute_corresponding_list/4 (replacement: substitute_corresponding_in_terms/4)
apply_substitution/2 (replacement: apply_substitution_in_term/3)apply_substitution/3 (replacement: apply_substitution_in_term/3)apply_substitution_to_list/2 (replacement: apply_substitution_in_terms/3)pred apply_substitution_to_list/3 (replacement: apply_substitution_in_terms/3)
apply_rec_substitution/2 (replacement: apply_rec_substitution_in_term/3)apply_rec_substitution/3 (replacement: apply_rec_substitution_in_term/3)apply_rec_substitution_to_list/2 (replacement: apply_rec_substitution_in_terms/3)pred apply_rec_substitution_to_list/3 (replacement: apply_rec_substitution_in_terms/3)
thread moduleThe following predicate and functions have been added:
init_thread_options/0set_min_stack_size/3spawn_native/5thread.mvar moduleThe following obsolete function has been removed:
init/1 (replacement: impure_init/1)thread.semaphore moduleThe following obsolete function has been removed:
init/1 (replacement: impure_init/1)time moduleThe following obsolete functions have been removed:
ctime/1 (replacement: localtime/4 and asctime/1)localtime/1 (replacement: localtime/4)mktime/1 (replacement: mktime/4)tree234 moduleThe following predicates have been added to this module:
foldl6/14foldl6_values/14foldr6/14uint16 moduleThe following functions have been added:
from_uint/2det_from_uint/1cast_from_uint/1rotate_left/2rotate_right/2unchecked_rotate_left/2unchecked_rotate_right/2set_bit/2unchecked_set_bit/2clear_bit/2unchecked_clear_bit/2flip_bit/2unchecked_flip_bit/2bit_is_set/2unchecked_bit_is_set/2bit_is_clear/2unchecked_bit_is_clear/2cast_from_uint8/1cast_to_uint8/1uint32 moduleThe following functions have been added:
from_uint/2det_from_uint/1rotate_left/2rotate_right/2unchecked_rotate_left/2unchecked_rotate_right/2set_bit/2unchecked_set_bit/2clear_bit/2unchecked_clear_bit/2flip_bit/2unchecked_flip_bit/2bit_is_set/2unchecked_bit_is_set/2bit_is_clear/2unchecked_bit_is_clear/2cast_from_uint8/1cast_to_uint8/1cast_from_uint16/1cast_to_uint16/1uint64 moduleThe following functions have been added:
cast_from_uint/1rotate_left/2rotate_right/2unchecked_rotate_left/2unchecked_rotate_right/2set_bit/2unchecked_set_bit/2clear_bit/2unchecked_clear_bit/2flip_bit/2unchecked_flip_bit/2bit_is_set/2unchecked_bit_is_set/2bit_is_clear/2unchecked_bit_is_clear/2cast_from_uint8/1cast_to_uint8/1uint8 moduleThe following functions have been added:
from_uint/2det_from_uint/1cast_from_uint/1rotate_left/2rotate_right/2unchecked_rotate_left/2unchecked_rotate_right/2set_bit/2unchecked_set_bit/2clear_bit/2unchecked_clear_bit/2flip_bit/2unchecked_flip_bit/2bit_is_set/2unchecked_bit_is_set/2bit_is_clear/2unchecked_bit_is_clear/2varset moduleThe following obsolete predicates have been removed:
merge_subst/4 (replacement: merge_renaming/4)merge_subst_without_names/4 (replacement: merge_renaming_without_names/4)The following functions and predicates have been added:
unname_var/2unname_var/3undo_default_names/2The type system now supports subtypes, which work in tandem with type conversion expressions (“coerce”). For example, the following defines a subtype real_color of a discriminated union type color:
:- type color
---> rgb(float, float, float)
; cmyk(float, float, float, float)
; named(string).
:- type real_color =< color
---> rgb(float, float, float)
; cmyk(float, float, float, float).A term of type real_color can be converted to a term of type color with coerce(Term). A term of type color can be converted to a term of type real_color if it has an appropriate inst. Subtypes share a common data representation with their base types, so the type conversions do not cost anything at runtime.
Field names no longer need to be unique within a module.
The compiler can implement tabling only when generating C code. When compiling a predicate that has a pragma memo specified for it in a non-C grade, it necessarily ignores the pragma, but normally it prints a warning about this fact. The compiler now supports a new attribute, disable_warning_if_ignored, that suppresses such warnings for a pragma memo if included in the pragma’s attribute list, like this:
:- pragma memo(predname/arity, [disable_warning_if_ignored])]).A pragma foreign_proc declaration can now include an attribute may_not_export_body that prevents its body (i.e. the foreign code) from being duplicated outside of the target file for that module by intermodule optimization. This is useful when the foreign code refers to types, functions, etc. that should be kept local to the target file of that module. Unlike the may_not_duplicate attribute, may_not_export_body does not prevent inlining of the foreign procedure into other procedures in the same module.
Many pragmas contain a name/arity pair for specifying the predicate or function they apply to; an example is
:- pragma inline(init/1).If the module in which this pragma occurs contains both a function init/1 and a predicate init/1, then this pragma is ambiguous. Traditionally, the Mercury compiler applied such ambiguous pragma to both the function and the predicate. The programmers who wished the pragma to apply to only one of them had to rename the other.
Now, pragmas that take a name/arity pair can specify whether they are intended to apply to a function or to a predicate by putting a func() or pred() wrapper around the name/arity pair, like this:
:- pragma inline(func(init/1)). % applies ONLY to func init/1.
:- pragma inline(pred(init/1)). % applies ONLY to pred init/1.This new syntax applies to all of the following kinds of pragmas:
check_termination
consider_used
does_not_terminate
fact_table
inline
loop_check
memo
minimal_model
mode_check_clauses
no_determinism_warning
no_inline
obsolete
promise_equivalent_clauses
promise_pure
promise_semipure
require_tail_recursion
terminates
type_specIf a command line first enables an optimization (say opt1), and then sets the optimization level to N with -O<N>, then the compiler will now keep opt1 enabled even if opt1 is not normally enabled at optimization level N.
Due to a bug fix, the --warn-unused-imports option is now stricter in warning about modules that are imported in the interface section but are not used in the interface section.
We have fixed parsing of reverse implication goals (A <= B).
By default, the compiler now checks some aspects of a module semantics when generating the .int and .int2 interface files for that module. (For example, it generates error messages for references to undefined types, insts and modes.) This new behavior can be switched off for now with the new option --no-halt-at-invalid-interface. This new option replaces the old --no-print-errors-warnings-when-generating-interface option, but once any problems caused by the new approach have been ironed out, we intend to delete the --halt-at-invalid-interface option as well.
In an earlier release, we extended the syntax of :- inst declarations to allow programmers to specify which type constructor’s values the inst is meant for. At that time, these functioned only as documentation, but the compiler now reports error messages for situations in which an inst that was declared to be intended for values of one type constructor is applied to values of another type constructor.
The new option --output-stdlib-grades outputs the grades in which the Mercury standard library is available with this compiler.
By default, the compiler now warns if the module being compiled has a name that shadows that of Mercury standard library module. The warning can be disabled using the new option --no-warn-stdlib-shadowing.
The new options --output-java-class-dir and --output-java-class-directory are now supported as synonyms for --output-class-dir.
The new option --halt-at-warn-make-interface causes the compiler to treat all warnings as if they were errors when generating interface files.
The new option --halt-at-warn-make-opt causes the compiler to treat all warnings as if they were errors when generating optimization files.
The new option --warn-potentially-ambiguous-pragma causes the compiler to generate a warning for all pragmas that include a name/arity pair, but lack a func() or pred() wrapper around it to indicate whether they are intended to apply to a function or to a predicate.
We have ported Mercury to Linux AArch64 (ARM64) systems.
The tools/configure_mingw_cross script has been replaced by tools/configure_cross. It now supports aarch64-linux-gnu and aarch64-linux-musl as targets (i.e. Linux on aarch64 with GNU or musl C libraries).
The list command may now call an external command to print source listings; the command is set using list_cmd. For example, the command could produce syntax highlighted source listings.
We have removed support for browsing terms as XML (browse --xml) as it was unmaintained and did not work any more. The browse --web command provides an alternative method for interactively exploring a term.
For news about earlier versions, see the HISTORY file.