Whenever is a Python library providing a Whenever type for representing date and time values in a more robust and intuitive way than native Python types. It's particularly focused on handling Daylight Saving Time (DST) transitions correctly and consistently, avoiding ambiguities and errors common with other approaches. Whenever objects store datetimes as UTC timestamps internally, but allow users to interact with them in local time using a specified timezone. They offer convenient methods for performing date and time arithmetic, comparisons, and formatting, while transparently managing DST transitions behind the scenes. This simplifies working with recurring events or schedules that span DST changes, eliminating the need for complex manual adjustments. The library aims to provide a clear and dependable way to manage date and time information across different timezones and DST rules.
No, COBOL does not inherently default to 1875-05-20 for corrupt or missing dates. The appearance of this specific date likely stems from particular implementations or custom error handling within specific COBOL systems. The language itself doesn't prescribe this default. Instead, how COBOL handles invalid dates depends on the compiler, runtime environment, and how the program was written. A program might display a default value, a blank date, or trigger an error message, among other possibilities. The 1875-05-20 date is potentially an arbitrary choice made by a programmer or a consequence of how a specific system interprets corrupted data.
Hacker News users discuss various potential reasons for the 1875-05-20 default date in COBOL, with speculation centering around it being an arbitrary "filler" value chosen by programmers or a remnant of test data. Some commenters suggest it might relate to specific COBOL implementations or be a misinterpretation of a different default behavior, like zeroing out the date field. Others offer alternative explanations, proposing it could represent the earliest representable date in a particular system or stem from a known data corruption issue. A few emphasize the importance of context and specific COBOL versions, noting that the behavior isn't a universal standard. The overall tone suggests the specific date's origin is uncertain and likely varies depending on the system in question.
The blog post explores optimizing date and time calculations in Python by creating custom algorithms tailored to specific needs. Instead of relying on general-purpose libraries, the author develops optimized functions for tasks like determining the day of the week, calculating durations, and handling recurring events. These algorithms, often using bitwise operations and precomputed tables, significantly outperform standard library approaches, particularly when dealing with large numbers of calculations or limited computational resources. The examples demonstrate substantial performance improvements, highlighting the potential gains from crafting specialized calendrical algorithms for performance-critical applications.
Hacker News users generally praised the author's deep dive into calendar calculations and optimization. Several commenters appreciated the clear explanations and the novelty of the approach, finding the exploration of Zeller's congruence and its alternatives insightful. Some pointed out potential further optimizations or alternative algorithms, including bitwise operations and pre-calculated lookup tables, especially for handling non-proleptic Gregorian calendars. A few users highlighted the practical applications of such optimizations in performance-sensitive environments, while others simply enjoyed the intellectual exercise. Some discussion arose regarding code clarity versus performance, with commenters weighing in on the tradeoffs between readability and speed.
JavaScript's new Temporal API provides a modern, comprehensive, and consistent way to work with dates and times. It addresses the shortcomings of the built-in Date object with clear and well-defined types for instants, durations, time zones, and calendar systems. Temporal offers powerful features like easy date/time arithmetic, formatting, parsing, and manipulation, making complex time-related tasks significantly simpler and more reliable. The API is now stage 3, meaning its core functionalities are stable and are implemented in current browsers, paving the way for wider adoption and improved date/time handling in JavaScript applications.
Hacker News users generally expressed enthusiasm for the Temporal API, viewing it as a significant improvement over the problematic native Date object. Several commenters highlighted Temporal's immutability and clarity around time zones as major advantages. Some discussed the long and arduous process of getting Temporal standardized, acknowledging the efforts of the involved developers. A few users raised concerns, questioning the API's verbosity and the potential difficulties in migrating existing codebases. Others pointed out the need for better documentation and broader community adoption. Some comments touched upon specific features, such as the plain-date and plain-time objects, and compared Temporal to similar date/time libraries in other languages like Java and Python.
Summary of Comments ( 61 )
https://news.ycombinator.com/item?id=43671308
Hacker News users generally praised the
wheneverlibrary for its focus on type safety and handling of daylight saving time (DST), which are common pain points in Python's datetime handling. Several commenters expressed interest in its approach using tagged unions for representing different kinds of time specifications. Some raised questions about the practical implications ofwhenever's immutability, particularly concerning performance in tight loops and modification of existing datetime objects. The discussion also touched upon alternatives likependulumandarrow, with some users suggestingwheneveroffered a fresh perspective on a persistent problem. A few commenters expressed skepticism about the library's complexity and the potential for over-engineering, preferring simpler solutions where possible.The Hacker News post about Whenever, a library for typed and DST-safe datetimes in Python, has generated a moderate amount of discussion, with a focus on existing solutions and the specific problems Whenever aims to address.
Several commenters point towards existing libraries and built-in functionalities in Python that already address some of the issues Whenever tackles. One commenter highlights the
zoneinfomodule introduced in Python 3.9, suggesting it provides similar timezone handling capabilities. Another mentions thePendulumlibrary as a potential alternative that offers user-friendly datetime manipulation. A third points out that thedatetimeobjects in Python already store timezone information, questioning the necessity of a new library.There's a discussion about the complexities of timezone handling in general. One commenter emphasizes the inherent difficulty of working with timezones and DST, suggesting that a comprehensive solution is challenging to achieve. Another adds to this by mentioning the "local time" ambiguity during DST transitions, where a specific time can exist twice or not at all, highlighting a common pain point.
The core value proposition of Whenever, namely its type safety, is also discussed. One user expresses appreciation for the static typing aspect, which can help prevent errors related to timezone handling at compile time. This resonates with another commenter who also sees value in the type hints provided by the library.
Finally, some commenters express skepticism about the library's usefulness. One suggests that using UTC consistently and only converting to local time for display purposes is a simpler approach. This sentiment is echoed by another who advocates for sticking with UTC and formatting time zones on output as a more straightforward solution.