Monthly Archives: September 2017

Java – Covariance, Contravariance and Invariance

https://stackoverflow.com/questions/8481301/covariance-invariance-and-contravariance-explained-in-plain-english

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Scala – Higher Kinded Type

https://stackoverflow.com/questions/6246719/what-is-a-higher-kinded-type-in-scala

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Scala – By Name Parameters

Syntax: => A By Name parameter will be evaluated when called

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Scala – conversion from for-comprehension to map, flatMap

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FP – expression vs statement

Expression: by combining value and function, it will generate the value with some possible side-effect Statement: standalone unit of execution without returning anything. Normally it has side effect. More information: https://fsharpforfunandprofit.com/posts/expressions-vs-statements/

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Cassandra – import snapshot tables(column family)

The following command will import a table(column family) to the destination Cassandra node.

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SHELL – tmux configuration example

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Functional Programming – Simple Explaining of Keyword

1. Functor -> Mappable 2. Currying -> Currying 3. Applicative -> Applicative 4. Monad -> Chainable 5. Monoid -> Aggregatable 6. Catamorphism -> Collapsable

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Monad – Definition of Monad with Monoid

Monad is a binding function to connect two functions where are different types between returning value and input argument. So Monad will allow to compose two incompatible functions. A monad is just a monoid in the category of endofunctors. This … Continue reading

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Monoid – Simple definition of Monoid

1. Closure: Two same type pair operation results a new result with same type. 2. Associative: Doesn’t matter or operation order wit a pair. 3. Identity: There is an identity can always result the original value. Integer plus: String concatenation: … Continue reading

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