init commit

.stack-work/

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# Changelog for concurrency-demo

## Unreleased changes

Copyright Yuanle Song (c) 2018

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# concurrency-demo

I want to practice using async, stm libraries to solve real world problems.

## problem: Dining philosophers problem

https://en.wikipedia.org/wiki/Dining_philosophers_problem

Five silent philosophers sit at a round table with bowls of spaghetti. Forks

are placed between each pair of adjacent philosophers.

Each philosopher must alternately think and eat. However, a philosopher can

only eat spaghetti when they have both left and right forks. Each fork can be

held by only one philosopher and so a philosopher can use the fork only if it

is not being used by another philosopher. After an individual philosopher

finishes eating, they need to put down both forks so that the forks become

available to others. A philosopher can take the fork on their right or the one

on their left as they become available, but cannot start eating before getting

both forks.

Eating is not limited by the remaining amounts of spaghetti or stomach space;

an infinite supply and an infinite demand are assumed.

The problem is how to design a discipline of behavior (a concurrent algorithm)

such that no philosopher will starve; i.e., each can forever continue to

alternate between eating and thinking, assuming that no philosopher can know

when others may want to eat or think.

## problem: Elevator simulator

Design an elevator which allows concurrent user input.

feature request:

- elevator requires time to accelerate and slow down

- elevator have a maximum capacity

- user can press Up/Down button at any level

- there can be any number of user at each floor

- user have normal behavior.

  - they don't stay in elevator forever

  - they press target floor when they are in

  - they leave when target floor is arrived

- a GUI is of much help for visualizing this system.

- when total floor is high, there are buttons that allow user to press which

  floor they want to go, to help elevator scheduling stops.

- 

import Distribution.Simple

main = defaultMain