Document GHC-66228 #344
Document GHC-66228 #344
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Fixes #90.
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| A [view pattern](https://ghc.gitlab.haskell.org/ghc/doc/users_guide/exts/view_patterns.html) allows pattern matching on the result of a function. | ||
| While most patterns share syntax with the corresponding expressions, there is no expression counterpart to view patterns. |
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| While most patterns share syntax with the corresponding expressions, there is no expression counterpart to view patterns. | |
| While most view patterns look like expressions, they can *only* be used as patterns. Sometimes GHC will think you've tried to use a pattern where it expected an expression, which is when this error arises. |
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I don't think that this edit results in a true statement. View patterns don't look like expressions, because they contain ->. Though I suppose this error could occur if a \ were omitted.
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"patterns share syntax with the corresponding expressions" sounded like a complicated way of saying "patterns look like expressions", but perhaps it is not as precise. :)
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That part makes sense. The key here, though, is that view patterns in particular do not share syntax with the expression fragment of the language, as -> is not a valid infix operator. I'll tweak the phrasing.
chreekat
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chreekat
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Thanks! The new phrasing makes sense to me.
Fixes #90.