[m-rev.] for review: a slot for each kind of operator

[Julien Fischer]

On Mon, 14 Nov 2022, Zoltan Somogyi wrote:

> Give each op class (infix, prefix etc) its own slot.
> 
> library/ops.m:
>     Instead of an op_table mapping a string to a list of one or more op_infos,
>     make it map the string to a single structure, the op_infos, which has
>     four slots, one each for infix, binary prefix, prefix and postfix
>     op information. This allows parsers and unparsers to go directly to
>     the kind of operator (e.g. infix or prefix) that they are interested in.
> 
> NEWS:
>     Announce the change.
> 
> compiler/parse_tree_out_term.m:
> library/mercury_term_parser.m:
> library/pretty_printer.m:
> library/stream.string_writer.m:
> library/string.to_string.m:
> samples/calculator2.m:
> tests/hard_coded/bug383.m:
>     Conform to the change. In several places, the new operator representation
>     allows the replacement of loops with direct lookups, and the replacement
>     of if-then-else chains with switches.
>
>     Add reminders about keeping two predicates in sync.

That's fine.

Julien.