What is Functional Programming? Part 5, Bindings
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N.B. this is unrelated to the concept of bindings in Silverlight and WPF.
One of my aha moments in learning F# occurred while I was reading Real World Functional Programming. Specifically, it was when the meaning of the let keyword really clicked. Before I explain, here are couple of samples:
let x = 42 let multiply a b = a * b
I was predisposed to interpret let as merely declaring a variable. but you will recall from the first post that we made a distinction between working with mutable “variables” and immutable “values”. Functional languages eschew mutability.
If you look up let in the official documentation and you’ll see that it is called a binding and it is very clearly described:
A binding associates an identifier with a value or function. You use the let keyword to bind a name to a value or function.
This also aligns with the concept of referential transparency we mentioned way back in the first post.
This may seem obvious or even a subtle distinction to make, but I think it is fundamental in understanding the functional approach.
After this clicked with me, I also realized that I can think of
let x = 42
as a function with no arguments that returns a value of 42. The distinction between binding to a value and binding to a function blurs. It is the Marriage of Value and Function.
Next stop, pattern matching in F#.
Published at DZone with permission of Christopher Bennage, DZone MVB. See the original article here.
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