Before starting installation of racket, some packages should be installed.
$ sudo apt-get install libfontconfig1-dev libcairo2-dev libpango1.0-dev libgtk2.0-dev
Visit https://download.racket-lang.org/ site and download “Unix Source and build packages”.
Raspberry Pi 3 must be connected to Internet when racket build has been stated. Many related files are downloaded while racket environment has been building.by