xmk (cont.)

Some updates after having put more thought into it.

xmk should make use of a build directory. Invoking the program with -i or --init should build that directory structure (xmk.d) based on the targets and platforms defined in the xmkfile.
The program should look for a file with the name xmkfile in current directory by default. If it can't find the file it will look for it in ./xmk.d/. But it's possible to invoke a specified xmkfile with the -f option. e.g.
xmk -f xmk.d/my_target.xmk
It's proven useful having scripts that write header files. So I decided it would be neat for the build system to make that explicit (rather than have scripts do the writing to files internally).
The consideration that follows is that helper functions to write script output to source files (while backing them up) might be equally handy. I realized that the current concept entirely lacks the recursive behavior that makes Make elegant.
All things considered I might be best off just writing a library in Ruby after all instead of implementing a parser for a custom language.

Anyways, here's the example xmkfile reflecting my current ideas

001  default(-t my_application -p linux -s debug)
002  list[] src = files(src/*.c, src/scene/*.c, src/engine/*.c)
003  src = filesr(src, *.c)
004  var obj_dir = obj/
005  var cc
006  var bin = bin/
007  list[] inc = -Iinclude
008  list[] lib 
009  list[] cflag
010  list[] sflag
011  list[] dep
012  
013  if debug
014      cflag << -g, -Wall, -Wno-switch, -Wno-unused-label
015      sflag << -DDEBUG
016      { echo Debug Mode! } print if verbose
017      { my_cmd }
018  end
019  
020  @my_application(0.2.0)
021      hedr h = header_create(my_header.h, xmk.d/include/$@)
022      for (platforms($@))
023          process($1)
024      end
025  end
026  
027  action linux
028      var v = version(-release)
029      lib << list({ `sdl2-config --libs` }, ), lSDL2_image, lSDL2_mixer
030      inc << -Imruby-2.1.0/include
031      obj_dir << linux
032      cc = gcc
033      bin << linux
034      if debug
035          h << #define VERSION $(version(-release))
036          v = version(-debug)
037          bin << -debug
038      else
039          h << #define VERSION $(version(-debug))
040      end
041      inc << headers() // expands to list of header files for this target-platform combination
042                       // with -i prefix
043      bin << $@-$!-$(v)
044      list[] obj = objects(src, obj_dir)
045      for(src, obj)
046          dep = dependencies({ $(cc) -M $1 $(cflags) $(inc) })
047          if dep_failed($2, dep)
048              { $(cc) -c $1 -o $2 $(cflags) $(inc) } print if verbose
049          end
050      end
051      { $(cc) -o $(bin) $($obj, ) $(lib) } print if verbose
052  
053  end
054