Eu instalei o cristal com homebrewbrew install crystal-lang. Consegui compilar e executar um "Olá Mundo!" programa, mas quando tento compilar o servidor http de exemplo (com uma pequena modificação), recebo um erro.

Servidor HTTP:

require "http/server"

port = 3000

server = HTTP::Server.new(port) do |context|
  context.response.content_type = "text/plain"
  context.response.print "Hello world! The time is #{Time.now}"
end

puts "listening on http://localhost:" + port.to_s
puts "listening on http://localhost:#{port}"
server.listen

Erro:

$ crystal server.cr                                                                                                                                        ~/sw/crystal/Lied-Today
ld: library not found for -lssl
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Error: execution of command failed with code: 1: `cc -o "/Users/Matt/.cache/crystal/crystal-run-server.tmp" "${@}"  -rdynamic  -lz `command -v pkg-config > /dev/null && pkg-config --libs libssl || printf %s '-lssl -lcrypto'` `command -v pkg-config > /dev/null && pkg-config --libs libcrypto || printf %s '-lcrypto'` -lpcre -lgc -lpthread /usr/local/Cellar/crystal-lang/0.21.1_1/src/ext/libcrystal.a -levent -liconv -ldl -L/usr/lib -L/usr/local/lib`

Eu tentei o seguinte:

Adicionandoexport LIBRARY_PATH="$LIBRARY_PATH:/usr/local/lib" para ~ / .zshrc.

e

$ xcode-select --install
$ xcode-select --switch /Library/Developer/CommandLineTools