Add documentation for language-supplied == and != on unions#28957
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bradcray wants to merge 1 commit into
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Add documentation for language-supplied == and != on unions#28957bradcray wants to merge 1 commit into
bradcray wants to merge 1 commit into
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While here, I reordered and changed the headings of a few sections in this chapter to match the records chapter, which I believe has received more attention in recent years. --- Signed-off-by: Brad Chamberlain <bradcray@users.noreply.github.com>
DanilaFe
approved these changes
Jun 10, 2026
| types, a compiler error is generated. | ||
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| These default comparisons consider two union values to be equal if (a) | ||
| both union have the same active field and (b) those fields are |
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bit of a nit, since it's clear what you mean, but "those fieldS" is mismatched with "same active field". Consider: "the respective values of this active field are..."
| union-type: | ||
| identifier | ||
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| The union type is specified by the name of the union type. This |
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I think it would help me to know that union-type is part of the type expression grammar. Because "union type is specified" is rough, and to me seems a little too close to "defined". I think perhaps we can adjust the opening paragraph of this section to say "The syntax of a union type expression is summarized as follows"?
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This is pre-existing (it just got moved), but I agree with the notion of improving it while I'm here.
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This adds a description to the language spec of the Chapel-supplied
==and!=operators on unions, as added in #14139 (apparently it didn't occur to me or my reviewer to add them then).While here, I reordered and changed the level of a few sections in this chapter to match the records chapter, which I believe has received more attention in recent years. Specifically, I moved the bit about declaring union types ahead of the section about referring to union types (since one must exist before you can name it, and naming it is strictly less interesting), and I moved assignment and these newly added comparisons into a "Common Operations" section to match records.