Clarify operator precedence description and table #4031
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This commit clarifies the operator precedence table as discussed in #4029 and the accompanying discussion of operator precedence and associativity. The commit made the following changes: * In the operators table, replaced the column that contained L, R, N, C, and X with a column listing associativites of 'left', 'right', 'non', 'chain', and 'list'. These single-letter abbreviations were used in S03, but are not currently used in elsewhere in Raku/Rakudo/the docs other than in a table in `language/functions`. * Made corresponding changes to the `language/functions` table. * Split the discussion of precedence and associativity into separate subsections for clarity. * Marked precedence levels that do not currently have any operator subroutines (these mostly do have *operators*, but those operators are special-cased by the compiler and aren't accessible to users). * Slightly expanded the associativity table and changed the example infix operator from `!` to `§` to avoid confusion with `prefix:<!>`. * Added a brief discussion of how associativity applies to non-infix operators and a note that setting the associativity for non-infix operators is NYI (see rakudo/rakudo#4779, rakudo/rakudo#4780). * Removed the table depicting associativity between unary operators, which misleadingly implied that creating right-associative unary operators is possible.
This was referenced Feb 12, 2022
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This PR clarifies the operator precedence table (as discussed in #4029) and clarifies/expands the accompanying discussion of operator precedence and associativity.
This PR makes the following changes:
'non', 'chain', and 'list'. These single-letter abbreviations were used in S03, but are not currently used in elsewhere in Raku/Rakudo/the docs other than in a table in
language/functions.language/functionstable.!to§to avoid confusion withprefix:<!>.associs implemented for unary ops.So, as I guess I should expect by now, a seemingly simple doc update grew into a more significant change than I expected, led me to realize I didn't understand something as well as I thought, and led me into an edge case that triggers a Raku bug! But, on the other hand, it also put me on the path to solving that bug – and it's one that's been around since 2014, so at least there's that 😁