Today-I-Leared (TIL)

Documenting software-things I learn almost everyday. Inspired by jbranchaud/til.

How This Will Be Organized

Start simple–one README.md (this one) for all entries. There will be no categorization yet because I am just getting started and want to mitigate the friction and frills. So, I'll start by simply keying each entry by time, fully knowing that as the entry list grows (hopefully)–I'll eventually index them differently.

Entries

2020-05-27

I was browsing the Scala 2.13.0 release notes and came across the change "Partial unification on by default". djspiewak's gist explained the motivation nicely–I've actually read it multiple times but today's pass-through led me to internalize the take away:

...if your type constructor takes multiple parameters, you should order them such that the parameters you expect users to vary (i.e. write a map function over, change frequently between functions, etc) should be right-most, while the parameters you expect to be consistent (i.e. the same at multiple unrelated places in the code) should be left-most.

Doing so will allow the compiler to help you in the edge cases. To me, this also rhymes with Either[Error, A].

2020-05-28

Timestamp timezone handling with Scala/Java and PostgreSQL can get tricky. There are layers of conversions and data types between application, driver, and the database itself. Today I was reminded of these nuances for both read and writes. UTC for storage is preferred, of course, but when rubber meets the road here are some nice resources I came across today to color this in practice:

PostgreSQL, All timezone-aware dates and times are stored internally in UTC.
Using a joda-time/JDBC app layer, avoid a LocalDateTime hop and jump to java.sql.Timestamp from joda DateTime (with timezone) via getMillis.
Great Stack Overflow answer that outlines the above and when one may want to deviate as well.

2020-05-29

Protobuf design for embedded platforms has considerations that can affect the design of the message. For nanopb in particular, variable-length types (e.g. string) within a oneof either needs a custom option specification for max size (with the implied memory overhead) or wrapped in it's own message. More details, reasoning and examples solutions here.

2020-06-01

Contents piped to pbcopy ends up in the clipboard.

openssl rand -base64 200 | pbcopy

2020-07-26

Excel VLOOKUP function can fail if target string with which the lookup refers to is greater than 255 characters. It will fail the match even if the lookup exists–and you will not be able to distinguish this from a true match failure unless you double check the work!

See this article for more details and a workaround. This bit me hard today.

2020-08-30

The existence of the book WebRTC for the Curious. Exactly what I wanted to learn–well written, free and fell into my lap! Plus an interesting article detailing the story of Zoom, when they used WebSockets, and then WebRTC.

michaelzg/til