中国历法

Chinese calandre is both solar and lunar, unlike western (pure solar) and Muslim (pure lunar):

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SQL vs NoSQL => MySQL vs MongoDB / Cloud Firestore

High performance ‘NoSQL’ Databases such as MongoDB or Google Cloud Firestore or Amazon DynamoDB, are ‘hot’ in web and mobile computing, where a lot more of READ & lesser Write operations to the backend cloud databases.

NoSQL Database is organized in Collections in which Documents are stored.

Pros:

  1. Speed
  2. Horizontal Scaling
  3. Flexible data structure

Con:

  1. Some duplicated data (but less significant relative to the 3 Pros.)

Cloud Firestore (fee charges, free trial plan only 1GB)

MongoDB in 2019:

ZDNet: MongoDB in 2019: Cloud, transactions, and mobile will be on the agenda.
https://www.zdnet.com/article/mongodb-in-2019-cloud-transactions-and-mobile-will-be-on-the-agenda/

Knowing Monads Through The Category Theory

https://dev.to/juaneto/knowing-monads-through-the-category-theory-1mea

While Mathematicians like to talk non-sensical abstract idea, Informaticians want to know how to apply the idea concretely:

Mathematical Parlance:

Monad = Monoid +Endofunctor

Monoid = Identity + Associative

Endo-functor = functor between 2 same categories

IT Parlance:

Monad is a ‘function’ to wrap the ‘side effects’ (exception errors, I/O,… ) so that function composition in ‘pipeline‘ chained operation sequence is still possible in pure FP (Functional Programming, which forbids side-effects).

Some common Monads: ‘Maybe’, ‘List’, ‘Reader’…
This allows monads to simplify a wide range of problems, like handling potential undefined values (with the Maybe monad), or keeping values within a flexible, well-formed list (using the List monad). With a monad, a programmer can turn a complicated sequence of functions into a succinct pipeline that abstracts away additional data management, control flow, or side-effects.[2][3]

Exploring Monads in Scala Collections

https://blog.redelastic.com/a-guide-to-scala-collections-exploring-monads-in-scala-collections-ef810ef3aec3