[Haskell-cafe] Naming scheme for partial functions

[Antoine Latter]

Yeah, that's a good point.Text and Bytestring (and other similar packages)
have been pushing the boundaries of 'unsafe' and are in wide use.


On Sun, Feb 9, 2014 at 11:38 PM, Michael Snoyman <michael at snoyman.com>wrote:

> I don't want to drag out bikeshedding either. But I *do* want to point out
> that mono-traversable also includes a function unsafeHead, separate from
> headEx. While headEx guarantees that it will throw an exception in the case
> of an empty Foldable, unsafeHead may crash your program. This is the same
> kind of distinction as vector and bytestring make between head and
> unsafeHead.
>
>
> On Sun, Feb 9, 2014 at 6:41 PM, Antoine Latter <aslatter at gmail.com> wrote:
>
>> Not that it matters, but I think I prefer the "Unsafe" suffix. I'm not
>> calling this version of "head" because I *want* an exception - I'm calling
>> it because I want "Unsafe" (non-typechecked) behavior - I'm asserting that
>> I've already validated some preconditions that aren't reflected in the type.
>>
>> But on the other hand I've always found functions like "fromMaybe" easier
>> to work with than functions like "fromJust".
>>
>> Enough bikeshedding! If it works in your packages that's fine, and these
>> are the sort of functions I have no complaints about reimplementing on my
>> own.
>>
>>
>> On Sat, Feb 8, 2014 at 11:25 PM, Michael Snoyman <michael at snoyman.com>wrote:
>>
>>> It means "throws an *ex*ception."
>>>
>>>
>>> On Sun, Feb 9, 2014 at 5:04 AM, Antoine Latter <aslatter at gmail.com>wrote:
>>>
>>>> What does "Ex" mean?
>>>>
>>>>
>>>> On Thu, Feb 6, 2014 at 8:59 PM, Michael Snoyman <michael at snoyman.com>wrote:
>>>>
>>>>> Thanks for the input. We ended up going with an `Ex` suffix, e.g.
>>>>> headEx, lastEx.
>>>>>
>>>>>
>>>>> On Fri, Feb 7, 2014 at 4:53 AM, Tikhon Jelvis <tikhon at jelv.is> wrote:
>>>>>
>>>>>> For what it's worth, OCaml's Core library does this with _exn, so
>>>>>> they would call a partial last "last_exn". I would actually prefer an
>>>>>> abbreviation of some sort (like exn) as long as it's a consistent
>>>>>> convention. Using a full word like "exception" or "partial" adds to much
>>>>>> noise in my opinion, especially if the base name (like "last") is shorter
>>>>>> than the suffix!
>>>>>>
>>>>>> Also, I think a suffix would be better than a prefix, if only to
>>>>>> group things conveniently when sorted alphabetically.
>>>>>>
>>>>>>
>>>>>> On Thu, Jan 30, 2014 at 9:36 AM, Atze van der Ploeg <atzeus at gmail.com
>>>>>> > wrote:
>>>>>>
>>>>>>> unprovenLast ?
>>>>>>> On Jan 30, 2014 6:33 PM, "Michael Snoyman" <michael at snoyman.com>
>>>>>>> wrote:
>>>>>>>
>>>>>>>> Greg Weber and I have been discussing some changes to
>>>>>>>> mono-traversable[1]. One of the modules we provide is Data.NonNull, which
>>>>>>>> provides total versions of functions like `last`. A change we're looking at
>>>>>>>> would require having a partial version of `last` defined in a separate
>>>>>>>> typeclass (IsSequence), which would allowing for more optimized
>>>>>>>> implementations of the total `last` function for datatypes which support it
>>>>>>>> (e.g., strict ByteStrings).
>>>>>>>>
>>>>>>>> But what should we name it? I'm sure everyone's familiar with the
>>>>>>>> `unsafe` naming convention, but that's not appropriate here: standard usage
>>>>>>>> shows `unsafe` meaning a function which can cause a segfault.
>>>>>>>>
>>>>>>>> I initially named it `partialLast`, but partial can also imply
>>>>>>>> partial function application. Greg brought up the idea of suffixing the
>>>>>>>> function with something like `Throws` or `Errors`, which I think I'm a bit
>>>>>>>> partial to myself[2].
>>>>>>>>
>>>>>>>> So my questions are:
>>>>>>>>
>>>>>>>> * Is there some already used naming scheme out there for partial
>>>>>>>> functions which I've missed?
>>>>>>>> * Do people have any ideas to throw into the mix?
>>>>>>>>
>>>>>>>> Michael
>>>>>>>>
>>>>>>>> [1] https://github.com/snoyberg/mono-traversable/pull/21
>>>>>>>> [2] Pardon the pun.
>>>>>>>>
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>>>>>>>>
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>>>>>>
>>>>>
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>>>>
>>>
>>
>
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