What is the compelling scenario for using Monads in C#
Let me state up front that I have an infantile understanding of Monads. I have read the various threads on Monads here and have done a few hours of study on the concept. I hardly feel comfortable with the term, but I think it is safe to say that I generally understand what a Monad is/does.
I'm a C# developer who is looking to improve the way I work. What would help me further in my Monaducation is see a real world application of a Monad in C# (ie via a linq SelectMany() or somesuch) that is clearly an improvement over other ways of solving the same sort of problem in oldskool C#.
Has anyone seen such a beast?
Here is one such scenario: you want to author a parsing library (a nice example of an embedded DSL), and you discover that the best ones are monadic parser combinator libraries. So you write it leveraging LINQ syntax sugars to author C# code that has the same structure as the grammar of the language you're parsing, and you get the benefits of an awesome programming model for on-the-fly semantic analysis and error-recovery. See this blog for a description.
寻找毕达哥拉斯三元组：
var r = from a in Enumerable.Range(1, 25)
from b in Enumerable.Range(a, 25-a)
from c in Enumerable.Range(b, 25-b)
where a*a + b*b == c*c
select new [] { a, b, c };
Here is one such scenario: you want to write code that makes sequential async calls (eg IO) without holding threads, but you don't want to write the hopeless tangle of spaghetti that the async programming model (BeginFoo/EndFoo) forces you into. So you can use a monad and LINQ sugars and write code that looks straight-line but it releases/switches threads throughout. See this blog for a short description.
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