add slice #104
add slice #104
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src/Data/String.purs
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| -- | Returns the substring at indices [begin, end). | ||
| -- | If either index is negative, it is normalized to `length s - index`, | ||
| -- | where `s` is the input string. An empty string is returned if either | ||
| -- | index is out of bounds or if `begin > end`. |
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Might want to say "or if begin > end after normalisation".
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I don't like the empty string being used as the error case. What else can we do? |
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Agreed. That is the default behaviour for javascript, but I could wrap the result in a |
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I don't know if this is better. This implementation doesn't check for the bounds, it just returns |
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Feel free to copy code from the implementation of |
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This is (necessarily) confusing code. It deserves some tests. ;) |
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The length calculations and bounds checking can be done in pure code. We should try to minimise the amount of JS. Basically, it should just expose |
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Ping @themattchan. With only a few added tests, we can land this PR. |
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Ok, I think the new tests exercise all the error conditions. |
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Thanks all! |
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