[ytti@ytti.fi ~/usr/git/sykemittari]% crystal build --release moi.cr
[ytti@ytti.fi ~/usr/git/sykemittari]% ~/usr/git/crystal/.build/crystal build --release moi.cr
./.crystal/home/ytti/usr/git/sykemittari/moi.cr/_main.o: In function `__crystal_main':
main_module:(.text+0x411a): undefined reference to `co_thread_init'
main_module:(.text+0x41e4): undefined reference to `co_set_data'
main_module:(.text+0x4a86): undefined reference to `co_get_data'
main_module:(.text+0x53ab): undefined reference to `co_get_data'
./.crystal/home/ytti/usr/git/sykemittari/moi.cr/_main.o: In function `*Fiber::new<&( -> Void)>:Fiber':
main_module:(.text+0x6a86): undefined reference to `co_set_data'
./.crystal/home/ytti/usr/git/sykemittari/moi.cr/_main.o: In function `*Fiber#resume<Fiber>:Void':
main_module:(.text+0x6f60): undefined reference to `co_get_data'
./.crystal/home/ytti/usr/git/sykemittari/moi.cr/_main.o: In function `*IO::FileDescriptor#unbuffered_write<IO::FileDescriptor, Slice(UInt8)>:Int32':
main_module:(.text+0x7559): undefined reference to `co_get_data'
./.crystal/home/ytti/usr/git/sykemittari/moi.cr/_main.o: In function `~fun_literal_12':
main_module:(.text+0x7e24): undefined reference to `co_get_data'
./.crystal/home/ytti/usr/git/sykemittari/moi.cr/_main.o: In function `~fun_literal_19':
main_module:(.text+0xb561): undefined reference to `co_get_data'
./.crystal/home/ytti/usr/git/sykemittari/moi.cr/_main.o: In function `*TCPServer@IO::Buffered#flush<TCPServer>:TCPServer':
main_module:(.text+0xc25a): undefined reference to `co_get_data'
./.crystal/home/ytti/usr/git/sykemittari/moi.cr/_main.o:main_module:(.text+0xe359): more undefined references to `co_get_data' follow
collect2: error: ld returned 1 exit status
Error: execution of command failed with code: 1: `cc -o "moi" "${@}"  -rdynamic  -lssl -lcrypto -levent -lrt -lpcl -lpcre -lgc -lpthread -ldl`
[1 ytti@ytti.fi ~/usr/git/sykemittari]% cat moi.cr
require "http/server"

server = HTTP::Server.new(1122) do |request|
  ##pp request.src
  ##pp request.dst
  HTTP::Response.ok "text/plain", "yaya"
end

server.listen
[ytti@ytti.fi ~/usr/git/sykemittari]%