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The Functional Programming Style
2:50Learn about the core concepts of the functional programming style.
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Before we get into using
methods syntax with LINQ.
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I wanna over a set of features in C# that
fit the style of functional programming.
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Functional programming
languages focus on computations
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as opposed to executing
a series of commands.
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C# is an object oriented language.
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However, many of the object oriented
languages out there have adopted elements
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of functional programming and give us the
ability to program in a functional style.
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LINQ queries are inherently functional
because as we write our queries,
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we are expressing what we want,
and not how we want it.
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If all this sounds a bit
confusing don't worry,
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I'll show you some examples
that should help clear it up.
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We'll only touch lightly on
functional programming for LINQ but
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we'll cover it in more
detail in a future course.
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There are some guidelines that functional
programming languages follow, and
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it can be helpful to keep them
in mind when writing code.
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The big one is that there
are no side effects.
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When you run a function,
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it should not modify anything
outside of the function scope.
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For instance, if we have a function
that evaluates a collection that exists
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outside the function, it shouldn't add or
remove anything from that collection.
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Another concept is that functions
are first class citizens.
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This means that functions
are treated like any other type and
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can be passed around as objects.
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We'll be going over delegates and other
function types in C# that let us do that.
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We also wanna make sure that a function
has the smallest scope and performs
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the least amount of work possible,
which is usually computational in nature.
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We should be able to treat
it like a piece of data.
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The function takes input and
gives us the result of the computation.
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We could replace the function
call with its expected result and
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everything would run the same.
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This is a good practice, in general.
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But it is definitely showcased when
applying functional programming concepts.
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And last but
not least is the use of expressions.
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For instance, instead of creating
a variable without a value and
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then running some kind of
logic to assign its value.
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You use an expression to assign
a value as you create it.
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This concept goes very well with LINQ.
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Applying these concepts in
your code has huge benefits.
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Your code becomes more readable,
easier to maintain and easier to test.
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However don't feel like you have to
use functional programming just for
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the sake of it.
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You can take these concepts and
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apply them in your applications
if it's the right fit.
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The goal is to help you
be a better programmer.
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You don't have to relearn how to
program in a functional way but you can
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take from these concepts and write code
that's cleaner and easier to maintain.
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