Add combiner as a cli tool

default.nix

@@ -14,11 +14,13 @@ pkgs.stdenv.mkDerivation {
  ];
 
  buildPhase = ''
- crystal build marka.cr
+ crystal build --release --progress --verbose marka.cr
+ crystal build --release --progress --verbose marka-combiner.cr
  '';
 
  installPhase = ''
  mkdir -p $out/bin
  mv marka $out/bin/
+ mv marka-combiner $out/bin/
  '';
 }

marka-combiner.cr

@@ -0,0 +1,16 @@
+require "./combiner"
+
+if ARGV.size != 1
+ STDERR.puts "A file to combine should be given as the only argument"
+ exit 1
+end
+
+begin
+ puts cat_file ARGV[1]
+rescue ex : CompileException
+ STDERR.puts ex.error
+ ex.stack.each do |s|
+ STDERR.puts "in #{s[:file]}:#{s[:line]}"
+ end
+ exit 4
+end