Grep

# A basic version of grep

use fs: ls, is_dir, is_file
use regex: re
use sys: argv

function walk(path)
   return fn*||
      try
         it = ls(path)
      catch e
         it = []
      end
      for x in it
         if is_dir(x)
            for y in walk(x)
               yield y
            end
         elif is_file(x)
            yield x
         end
      end
   end
end

function grep(pattern,path)
   r = re(pattern)
   return fn*||
      for id in walk(path)
         try
            s = read(id)
         catch e
            continue
         end
         for n,line in re("{n}").split(s).enum()
            if len(r.list(line))>0
               yield [id,n,line]
            end
         end
      end
   end
end

function main()
   pattern = argv[1]
   path = argv[2]
   for t in grep(pattern,path)
      print("File: {}\nLine: {}\n{}\n"%t)
   end
end

main()