Chapter4 answers #4
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🎉 Fantastic work!
Thank you so much for taking this course! I hope you had fun 🕺 🎤
We would really appreciate your feedback on the course!
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| @@ -267,7 +276,8 @@ instance Functor Maybe where | |||
| fmap _ x = x | |||
| @ | |||
| -} | |||
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| -- The type of x is a, and that implementation does not change the | |||
| -- type of a to b, so the return type is wrong | |||
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| (<*>) :: Secret e (a -> b) -> Secret e a -> Secret e b | ||
| (<*>) = error "(<*>) Secret: Not implemented!" | ||
| Trap e <*> _ = Trap e | ||
| Reward f <*> x = f <$> x |
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Nice work on reusing Functor instance for Secret! 🗺️
| -- weird expected behavior, I personally assumed it would be the same as | ||
| -- liftM2 (&&), but that was not the case | ||
| andM :: (Monad m) => m Bool -> m Bool -> m Bool | ||
| andM = error "andM: Not implemented!" | ||
| andM b1 b2 = b1 >>= (\b -> if not b then pure b else (&&) b <$> b2) |
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The ordinary && if lazy on the second argument. Meaning that if it meets False as the first argument, there is no need to calculate another arg. In andM we would like to keep the same behaviour, so the
Just False `andM` _
should be Just False 🙂
| @@ -673,7 +712,24 @@ Specifically, | |||
| ❃ Implement the function to convert Tree to list | |||
| -} | |||
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| -- this felt a little easy for a final boss xD | |||
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There's already an issue for that 😅
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Thank you very much for all the help and the course. |
Solutions for Chapter 4
The final chapter! And the one with content I always struggled, but was very good to understand with your explanations!
cc @vrom911 @chshersh