Add real error messages for associativity errors#3315
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garyb merged 4 commits intopurescript:masterfrom Apr 24, 2018
Merged
Add real error messages for associativity errors#3315garyb merged 4 commits intopurescript:masterfrom
garyb merged 4 commits intopurescript:masterfrom
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garyb
commented
Apr 24, 2018
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| import Prelude | ||
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| feq f x y = f <$> x == f <$> y |
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This case was a little surprising, but GHC has an error for it too:
Prelude> let f x y = f <$> x == f <$> y
<interactive>:10:13:
Precedence parsing error
cannot mix ‘<$>’ [infixl 4] and ‘==’ [infix 4] in the same infix expression
<interactive>:10:13:
Precedence parsing error
cannot mix ‘==’ [infix 4] and ‘<$>’ [infixl 4] in the same infix expression
garyb
commented
Apr 24, 2018
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| import Prelude | ||
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| a = true == true == true |
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GHC again:
Prelude> True == True == True
<interactive>:11:1:
Precedence parsing error
cannot mix ‘==’ [infix 4] and ‘==’ [infix 4] in the same infix expression
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I think we’ll need to update the docs for fixities now - it sounds to me like the docs I wrote might not all still apply, and there might be cases where the examples in the docs now produce these errors. |
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Ah ok, I'll open an issue over there as a reminder. |
This was referenced Apr 24, 2018
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Resolves #3310
The code for generating the errors is kinda absurd as it's more complicated than the actual rebracketing code (since using parsec hides a bunch of that), but whatyagonnado.