This repository is meaningless for any person except myself since it's just a time trial to measure the time to create a simple mathmatical expression evaluator.

My aim is to measure my coding speed and memory skill at my own game mainly. The following rules exist in this challenge:

• Don' copy external resource and paste it into my codes directly. But pasting it into my brain is OK.
• If at all possible, don't refer API documentation. When API documentation is refered, write commit comment about that.
• Write commit comment about my mistake(typo is included, of course) in progress whenever it occurs.
• Advance preparation to commit information to memory is not problematic.
• Don't use editor/IDE completion features.
• This project must be simple sbt project at the end.
• The scala programs must be under "com.github.kmizu" or/and its sub-packages.
• By executing sbt "run input.txt", the mathematical expression in the file must be evaluated correctly. A mathematical expression must support integer literal, four arithmetic operators, and parentheses to enclose an expression.

• It tooks about 20 minutes until the completion. Time without coding is included in 20 minutes.
• I made three mistakes. Two mistakes are related to forgetting and one mistake is related to error.
• LOC is 27.