Context-aware ExactPrint grafting for HsExpr #1489
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isovector
commented
Mar 4, 2021
Ailrun
reviewed
Mar 4, 2021
| needsParensSpace ExplicitList{} = (All False, All False) | ||
| needsParensSpace RecordCon{} = (All False, All False) | ||
| needsParensSpace RecordUpd{} = mempty | ||
| needsParensSpace _ = mempty |
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Do we have a case that "Needs paren" and "Needs space"" are different?
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Today, no, but in general they are not the same. For example, if you are grafting into a + _, you need the space but you only need parens if you contain an operator with associativity < 5. I plan to implement this in the future, and want to leave the path open, but #1486 is a high-priority bug to fix.
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I'm planning on merging this by end of day if nobody disagrees! |
konn
approved these changes
Mar 5, 2021
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In #1486, it's pointed out that always inserting a leading space when grafting trees will break layout (and thus the parse) if you're grafting into a
doblock. Yikes.This PR adds a function
graftExprwhich tracks the tree context of the graft's destination. If the immediate parent of the destination is a function application, or a few other things, we need to insert that space.And hey, while we're looking at context, let's use it to determine if we need parentheses!
Fixes #1486