Add new practice exercise split-second-stopwatch
#749
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| , Ok (PreviousLaps [ "01:23:45", "04:01:40" ]) | ||
| , Ok (CurrentLap "08:43:05") | ||
| , Ok (Total "14:08:30") | ||
| , Ok (PreviousLaps [ "01:23:45", "04:01:40", "08:43:05" ]) |
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The Output type introduced on top is only used for this exercise, it's the only one where we need to assert the values of different types. It's a little verbose, but it's the best I could come up with.
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This is going to make any test failures hard to read. Not sure what the other solutions are, but maybe asserting on all the fields all the time, instead of picking out one for each assertion?
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| type Stopwatch | ||
| = Stopwatch | ||
| { state_ : State |
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what are the underscores for?
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| start : Stopwatch -> Result String Stopwatch | ||
| start (Stopwatch ({ state_ } as stopwatch)) = |
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Maybe we could use a finite state machine here, instead of using Result (and in the other places)?
| , Ok (PreviousLaps [ "01:23:45", "04:01:40" ]) | ||
| , Ok (CurrentLap "08:43:05") | ||
| , Ok (Total "14:08:30") | ||
| , Ok (PreviousLaps [ "01:23:45", "04:01:40", "08:43:05" ]) |
There was a problem hiding this comment.
This is going to make any test failures hard to read. Not sure what the other solutions are, but maybe asserting on all the fields all the time, instead of picking out one for each assertion?
This is a brand new one fresh from the problem specs.
Originally, I thought that would be an exercise about time, but really it's much more suited to be our first practice exercise about
opaque-types.In reality,
Stopwatchcan be implemented as atype alias, but I opted not to do that in the example solution to push students to use proper opaque types. Of course, we can't stop them from using type aliases, but we could add an analyzer check with some appropriate message. What do you think?