Friendly error when using multiple spreads #4265
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| ParseErrorType::ListSpreadWithAnotherSpread => ( | ||
| "I wasn't expecting a spread here", | ||
| vec![ | ||
| "Hint: use list.append(list1, list2) to join two lists.".into(), |
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Not sure we want to recommend this, it's normally the wrong thing to do
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Yea, I guess it is likely that the problem is modeled poorly. Perhaps we can add that as a comment, or suggest a common "pattern" to model such problems better.
On the other hand, you could argue that it is still helpful for newcomers. You have to type [..xs, ..ys] to get the recommendation, so I think it is pretty clearly what you are trying to do.
What do you think?
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We generally don't want to people to append lists, so helping them to do it would be counterproductive.
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I didn't know about snapshot testing - that's cool! I've added the test. |
| ┌─ /src/parse/error.gleam:5:13 | ||
| │ | ||
| 5 │ [..xs, 4, ..ys] | ||
| │ ^^ I wasn't expecting a spread here | ||
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This is a bit confusing to me, the spread there is technically correct, the problem is there's a prior spread that shouldn't have been there. Maybe it could be pointing to the one that is not last and highlight how there can only be one at the end of the list?
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Having the error at anything that follows the first spread would be fine and possibly easier to implement. The error can say that the spread must be the last thing in the list.
| ┌─ /src/parse/error.gleam:5:13 | ||
| │ | ||
| 5 │ [..xs, 4, ..ys] | ||
| │ ^^ I wasn't expecting a spread here | ||
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Having the error at anything that follows the first spread would be fine and possibly easier to implement. The error can say that the spread must be the last thing in the list.
| location: SrcSpan { start: 39, end: 41 }, | ||
| } | ||
| ); | ||
| } |
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Could you remove the two unit tests please 🙏
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Thank you! |
This was unexpected to me, so figured other new gleamers could trip over it as well
(and an excuse to play with the compiler :))