Programming.log - a place to keep my thoughts on programming

摘要： When executing a pipe, each command of the pipe is in a separate process from the Bash process. The variable modified by the function is lost. The exit code of the function is also lost, because the exit code of a pipe is the exit code of the last command of the pipe. 阅读全文

摘要： This tool is used to generate the object graph of a Git repository. The primary purpose is to help Git learners better understand the Git data model through visualization. 阅读全文

摘要： Product type guarantees that if you have a function of type Y -> X1 and a function of type Y -> X2, you must have a unique function of type Y -> X1 x X2 satisfying the property. Sum type guarantees that if you have a unique function of type X1 -> Y and a function of type X2 -> Y, you must have a function of type X1 ∐ X2 -> Y satisfying the property. 阅读全文

摘要： Introduces a general pattern named Lazy Iterator for converting recursive traversal to iterator. It can be used to simulate generator (the "yield" keyword) in languages like Python. 阅读全文

摘要： The point of Monad is composability. In the green category, T -> Monad and U -> Monad 阅读全文

摘要： A general function to transform the future of an initial state to the future of its final state. 阅读全文

摘要： Functions are born in a harmonious ecosystem. Whenever you write a function, you automatically enjoy compose, functors, monads, monad transformers... 阅读全文

摘要： The algorithm for supporting distributed MVCC based multi-row transactions on top of a distributed key-value database with single-row transaction support. 阅读全文

摘要： The core ideas of Paxos protocol: 1) Optimistic concurrency control (variant 2). Hold a "preemptible lock" first, try updating, restart on denial; 2) Quorum as a logical unit of acceptor for choose operation. A value is chosen iff it's accepted by a quorum, which implies from the proposer's perspective the choose operation is atomic, it's all or nothing, it's either accepted by a quorum or it isn't. 阅读全文

摘要： fmap :: (T -> R) -> Functor<T> -> Functor<R> lifts a function of type T -> R into a function of type Functor<T> -> Functor<R>; flatMap :: (T -> Monad<R>) -> Monad<T> -> Monad<R> lifts a function of type T -> Monad<R> into a function of type Monad<T> -> Monad<R>. 阅读全文