Notion

Base64: Standardized way to turn any data (binary or text) into a text string without any large problem. Note that the size of the data will increase significantly (~ one third).
grpc: Add rpc call to protobuf serialization layer
Functional Programming: The meaning of the programs is centered around evaluating expressions rather than executing instructions.

This is the key to functional programming’s power — it allows improved modularization

In a functional program what is important is that it is a value oriented language; what we are building are sentences made from different values and higher order functions. The types and higher order values are defining the grammar of those sentences.

Algebraic Data Type: A struct or new type, composed from other types either as a product or a sum type.

Name	Member	Inhabitant
Void		0
Unit	()	1
Bool	True, False	2

Going from there you can define by sum a type with 3 elements:

data Add a b = AddL a | AddR b
-- or
data Either a b = Left a | Right b

-- if a is Bool and b is () you have got:
addValues = [AddL False, AddL True, AddR ()]

You can also use a product type with Mul:

data Mul a b = Mul a b
-- or
data (,) a b = (a, b)

mulValues = [Mul False False, Mul False True, Mul True False, Mul True True]

Abstract Data Type (ADT): A data type is said to be abstract when its implementation is hidden from the client. ADT’s are types which encapsulates a set of operations. The concept originates from CLU (Liskov, 1972) :

Modules → Partitions → ADTs

The canonical example is a Stack for which we define a set of operations including a way to construct/get a new empty Stack.

This is very different and even dual to the concept of objects in OO. ADT operations belongs to its datatype whereas OO objects are implemented as collections of observations (methods) that can be performed upon them. The focus on observations, rather than construction, means that objects are best understood as co-algebras.

Hash Value

Hashing is a transformation AnyText → TextWithFixedSmallerSize (array of bites) called digest or hash value with the following (ideal) properties:

it is quick to compute
it is not reversible: you cannot get anyText from the digest
the digest is unique so that two different AnyText will always have a different digest.

The idea is to store this mapping in a database so that you use digest as a representation for AnyText (the digest becomes the id/handle for the Text). Given such a mapping you can also hash AnyText, get a digest and do a lookup in the table to see if the mapping already exists.

CAP

Consistency
Availability
Partition

nibble

Half of one byte. So 4 bits/digits → 16 values

subroutine

Synonym for function

subtype

Circle <: Shape

Object Orientated Programming: Objects by definition include mutable state → intensional object identity !!
SWOT: Strength / Weakness / Opportunity / Threats