Functional Programming: This thread is like a burrito

The Something Awful Forums > Discussion > Serious Hardware/Software Crap > The Cavern of COBOL > Functional Programming: This thread is like a burrito

brap: Aug 23, 2004; Grimey Drawer

Bloody posted:

What's a monad?

I'm sorry for being another person to talk about this.

A monad is when you put a wrapper around a value and make it so it's only possible to access that value with a callback. It's an extremely simple and general concept when you get to the heart of it. Ever use Nullable<T> in C#? Consider an example like this:

code:

Nullable<int> nullable1 = 4;
Nullable<int> nullable2 = null;

var result1 = nullable1 + 2; // Returns a nullable containing the value 6.
var result2 = nullable2 + 2; // Since this nullable contained a null, this operation returns null.

For result1 and result2, C# is automagically providing a function to the Nullable<int> which, given an int, returns that int plus 2. The nullable monad decides whether or not to make use of the function, depending on whether or not it has a value to provide to the function!

There's a zillion uses of this pattern that will make your programming life better. Look at all the LINQ stuff, Task<T>, Func<T>, etc. if you're in the .NET world.

# ¿ May 1, 2015 06:49

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# ¿ Apr 28, 2024 21:55

brap: Aug 23, 2004; Grimey Drawer

I spent a lot of time with How to Design Programs in supplement to my regular college programming classes and it was incredibly helpful. It's what I recommend to everyone starting. It really strips away the stuff beginners should not be worrying about and helps beginners build good habits.

I haven't worked with the scheme book people mention often in the same breath but I'm sure it's good too.

# ¿ May 1, 2015 17:37

brap: Aug 23, 2004; Grimey Drawer

I really think whoever devised the wikipedia definition of monad should be shot.

Math articles on Wikipedia in general are impenetrable gibberish.

# ¿ May 4, 2015 16:38

brap: Aug 23, 2004; Grimey Drawer

Seriously, IO and effects and stuff has nothing to do with the definition of a monad. Set that aside when you first learn about them and try playing with a conceptually simple monad instance like Maybe.

# ¿ Apr 19, 2016 17:50

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