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Hello, World!
2:22In this video we will use the scala REPL for an up and running example of Scala.
There are two ways of
creating variables in Scala.
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The preferred way is by creating
a constant using the key word val.
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This way of creating a variable supports
the second idea of functional programming,
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as the contents of a val
cannot be changed.
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Additionally, you can create
a mutable variable in Scala
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by using the key word var
whose contents can be changed.
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Let's see how this works in the REPL, the
interactive shell, which we can get to by
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opening up a terminal in a Mac or command
prompt in Windows and typing Scala.
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Let's open up the terminal
to start the Scala REPL.
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REPL stands for read,
evaluate, print, and loop, and
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it's very useful in
evaluating expressions.
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Here, we've created
a variable name greeting.
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A constant whose values cannot be changed.
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Attempting to reassign
the value of variable greeting
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will throw a reassignment to val error.
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Let's take a look at that.
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Let's take a similar approach, but
with a mutable variable this time.
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We've created a variable called message,
which contains the string, hello world.
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Because vars are mutable,
we can reassign its value.
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In both instances,
you may have noticed two things.
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First, we aren't required to provide a
semicolon at the end of the statement, and
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that's because Scala supports
semicolon inference.
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Second, we didn't have to
specify the parameter type.
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That's because scala has a built
in type inference mechanism
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which allows it to figure out what
the type of variable should be.
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Although not recommended,
we can always supply the semicolon or
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the type information if
we really wanted to.
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Let's take a look.
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Awesome, we learn how to create values and
variables in Scala.
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In the next video, we will create our
first Scala app and learn about functions.
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See you there!
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