Add limitMaybe_, offsetMaybe_ + tests #633
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| => Maybe Integer -> Q be db (QNested s) a -> Q be db s (WithRewrittenThread (QNested s) s a) | ||
| limitMaybe_ (Just limit') (Q q) = | ||
| Q (liftF (QLimit limit' q (rewriteThread (Proxy @s)))) | ||
| limitMaybe_ Nothing (Q q) = Q (unsafeCoerce q) |
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I think you should be able to use rewriteThread
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Sorry, could you give a hint on how that would look? I haven't grokked this stuff yet...
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@tathougies I'm going through old PRs in and was blocked on this question -- could you clarify?
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Yeah, so the type doesn't match I believe because (QNested s) doesnt unify with WithRewrittenThread (QNested s) s. The latter unwraps one level of QNested`, which is what the rewriteThread function is fro. I believe if you do.
rewriteThread (Proxy @s) q instead of the unsafeCoerce q , that should work.
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I tried some stuff like that and wasn't able to get it to work:
Building library for beam-core-0.9.2.1..
[28 of 32] Compiling Database.Beam.Query.Combinators
/home/tom/tools/beam/beam-core/Database/Beam/Query/Combinators.hs:347:32: error:
• Couldn't match type: WithRewrittenThread
s0 s (QM be db (QNested s) a)
with: Control.Monad.Free.Church.F
(QF be db s) (WithRewrittenThread (QNested s) s a)
Expected: QM be db s (WithRewrittenThread (QNested s) s a)
Actual: WithRewrittenThread s0 s (QM be db (QNested s) a)
The type variable ‘s0’ is ambiguous
• In the first argument of ‘Q’, namely
‘(rewriteThread (Proxy @s) q)’
In the expression: Q (rewriteThread (Proxy @s) q)
In an equation for ‘limitMaybe_’:
limitMaybe_ Nothing (Q q) = Q (rewriteThread (Proxy @s) q)
• Relevant bindings include
q :: QM be db (QNested s) a
(bound at Database/Beam/Query/Combinators.hs:347:24)
limitMaybe_ :: Maybe Integer
-> Q be db (QNested s) a
-> Q be db s (WithRewrittenThread (QNested s) s a)
(bound at Database/Beam/Query/Combinators.hs:345:1)
|
347 | limitMaybe_ Nothing (Q q) = Q (rewriteThread (Proxy @s) q)
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@tathougies pinging again, would love to get this merged
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@tathougies another ping, please help! or maybe we could just merge as-is?
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@tathougies here is the ping for 2024 :)
| => Maybe Integer -> Q be db (QNested s) a -> Q be db s (WithRewrittenThread (QNested s) s a) | ||
| offsetMaybe_ (Just offset') (Q q) = | ||
| Q (liftF (QOffset offset' q (rewriteThread (Proxy @s)))) | ||
| offsetMaybe_ Nothing (Q q) = Q (unsafeCoerce q) |
Heard there was a major release cycle coming :).
This would resolve #491.
Note: I used an
unsafeCoerceto implement these. I think it's fine and the tests pass, but maybe there's a nicer way to wrangle the types here?