https://issues.dlang.org/show_bug.cgi?id=21215

Ajieskola@gmail.com changed:

           What    |Removed                     |Added
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             Status|NEW                         |RESOLVED
                 CC|                            |Ajieskola@gmail.com
         Resolution|---                         |INVALID

--- Comment #1 from Ajieskola@gmail.com ---
This is intended behaviour.

When recurrency function is called with 0, sequence.dropExactly is called with 0ul - 1, which overflows to ulong.max. The code is multiplying the previous factorial ulong.max times.

It is not an infinite loop literally, but would presumably take thousands of years to complete.

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