Installing Swift on non-Apple platforms is a bit of a headache, and unless you’re on exactly the supported version of Ubuntu, you need to compile Swift from source, which is an hours-long process, and not for the faint of heart.
agreed, though i’ve never had to compile it from source just to get it to run on my platform. the official swift binaries support a lot more versions of Ubuntu that they say they do,, the 16.10 binary runs just fine on 17.10. that said it’s not really obvious that you have to install clang to make swift work (i don’t remember this being documented anywhere!). And there’s a lot of compiler bugs that happen on linux that people just really don’t seem to care about.
$ swift
Welcome to Swift version 4.2-dev (LLVM 70f121e1f0, Clang 4c555650a6, Swift bb9532c588). Type :help for assistance.
1> 2 + 2
error: Couldn't lookup symbols:
swift_beginAccess
swift_endAccess
1>