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Clarify type signature requirement in task 1 #598

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Sep 13, 2023
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Clarify type signature requirement in task 1 #598

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Clarify type signature requirement in task 1
ceddlyburge Sep 9, 2023
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Make instructions a bit more specific about exensible records and pha…
ceddlyburge Sep 13, 2023
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6 changes: 4 additions & 2 deletions exercises/concept/treasure-factory/.docs/instructions.md
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Expand Up @@ -29,12 +29,14 @@ A `Chest` should hold the same data as a `TreasureChest` and should have two typ
Note that because `Chest` is using a phantom type, and should therefore be opaque to prevent its use anywhere outside of the `TreasureFactory` module.
In this case, it is not even exposed at all.

`secureChest` should take a `Chest` without specific conditions and return one wrapped in a `Maybe` that has the extra condition `securePassword : ()`.
`makeTreasureChest` should take a `List` of `Chest` without specific conditions and return a `List` of `Chest`, with the duplicates removed, and the extra condition `uniqueTreasure : ()` added.
Edit the type signatures of `secureChest` and `uniqueTreasures` to add the constraints using extensible records as phantom types.
`secureChest` should take a `Chest` without specific conditions and return a `Maybe Chest`, with the extra condition `securePassword : ()` in its phantom record.
`uniqueTreasures` should take a `List Chest` without specific conditions and return a `List Chest`, with the extra condition `uniqueTreasure : ()` added to the phantom record.

~~~~exercism/note
Elm tests have access to exposed functions, but not to type signatures, it is therefore impossible for tests to verify that you are using the right signatures.
Of course, the strongest indication that you have the right signatures is to succeed in getting the module and tests to compile and run.
We hope to use the analyser to check this in the future, but for now, no check is performed.
~~~~

## 2. Select secure chests
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