Concept Algebraic Data Types with exercise #1110
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This formulation of Valentine's Day requires the student to use general (i.e. not literal-specific) pattern matching, which has not yet been introduced. I expected Valentine's Day to be used for Pattern Matching. Either way, an extra exercise needs be found for the Concept not paired with Valentine's Day. |
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@MatthijsBlom What do you think of Ticket Please for PM2? it seems better suited for a more in-depth look a PM as it makes use of de-structuring, record updates, and requires previous exposure to tuples, records and ADTs. |
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Well, ALLOWED-TO-NOT-COMPILE implies that the stub doesn't compile. But, this current stub does compile. Therefore, it's forbidden to add ALLOWED-TO-NOT-COMPILE. If the stub cannot be tested, you're supposed to use DONT-TEST-STUB instead. |
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@petertseng thanks, that took care of it. |
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https://github.com/exercism/haskell#stub-solution is the documentation for DONT-TEST-STUB. I find no documentation for STUB-ALLOWED-TO-NOT-COMPILE. I wouldn't really like to advertise those features. Every instance of those means more manual work that has to be done to make sure the stubs are good, and more manual work means the track is harder to maintain. |
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I must admit it is quite embarrassing the problem, and its solution, can be found clearly spelled out in a file I updated just a couple days ago... 😊 |
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| rateActivity :: Activity -> Approval | ||
| rateActivity activity = | ||
| case activity of |
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This implementation uses case, which I don't think is being taught in the prerequisites, correct? If so, we'll need to add another exercise to teach that or rewrite this to use the pattern matching functionality that was already introduced.
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case is introduced in this concept (last paragraph of introduction.md)
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All previous comments addressed. Just pending decision on introducing |
| case rateActivity Chill of | ||
| No -> True | ||
| _ -> False |
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Surprising. It correctly rejects incorrect implementations, but has the disadvantage of not showing the correct vs incorrect result. I wish there were a way to do that.
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@petertseng Feel free to merge as you feel fit. |
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| - Chill out: no. | ||
| - Watch a movie: yes if it is a romantic movie; otherwise, no. | ||
| - Go to a restaurant: yes if the cuisine is Korean, maybe if it is Turkish. | ||
| - Take a walk: yes if the walk is less than three kilometers; maybe if it is between three and five kilometers (inclusive); otherwise, no. |
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I added the (inclusive) here. Even though I think it was fairly obvious it's inclusive (if it wasn't, the only value that gets a Maybe would have been 4, the answer for 3 would have been undefined), I wanted to be explicit anyway.
| it "walk 2 kilometers rated yes" $ | ||
| case rateActivity (Walk 2) of | ||
| Yes -> True | ||
| _ -> False | ||
| it "walk 3 kilometers rated maybe" $ | ||
| case rateActivity (Walk 3) of | ||
| Maybe -> True | ||
| _ -> False | ||
| it "walk 5 kilometers rated maybe" $ | ||
| case rateActivity (Walk 5) of | ||
| Maybe -> True | ||
| _ -> False | ||
| it "walk 6 kilometers rated no" $ | ||
| case rateActivity (Walk 6) of | ||
| No -> True | ||
| _ -> False |
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there were not any tests for walk, before I added them.
First stab at introducing ADTs and the associated exercise (Valentines Day) to get the conversation and edits started.