FreeBSD includes the Crystal compiler in the ports tree, starting from version FreeBSD 11.0.
Currently, it is only available for aarch64 and amd64 platforms.
When building Crystal code with the --release flag on FreeBSD, the --no-debug flag should be added too in order to avoid LLVM assertion errors.
Crystal is available as a compiled package. However, it might not be the most recent version available.
sudo pkg install -y crystal shards
For building Crystal yourself, the required installation is available in the ports tree.
If the ports collection is not already installed, it can be downloaded using portsnap fetch or git clone https://github.com/freebsd/freebsd-ports.
sudo make -C/usr/ports/lang/crystal/ reinstall clean sudo make -C/usr/ports/lang/shards/ reinstall clean
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https://crystal-lang.org/docs/installation/on_freebsd.html