To get started with Plait, download Racket, install it, start DrRacket, and install the plait package using DrRacket’s Install Package... menu item in the File menu.
Then, in the top part of the DrRacket window, type
and click the Run button (or use the keyboard shortcut shown in the Racket menu). In the bottom part of the window, type 1 and hit Return, and you should see this result:
In other words, the expression 1 has type Number, and the value of the expression is 1.
In this tutorial, we will mostly show expressions as if typed in that bottom area. You can also put the expressions in the top area and hit Run again, but in that case, the type of the result will not print before the result.
In a few places, the tutorial shows lines that include a semicolon, ;. A semicolon starts a comment that continues to the end of the line. For examples of other comment forms, see "demo.rkt".