predicate whether a file exists in the search path

exist_in_search_path.rb

#
# Which implementation do you prefer?
#

# 1.
def exist_in_search_path_1?(file, paths)
  paths.split(":").each { |dir|
    return true if FileTest.exist?(File.expand_path(file, dir))
  }
  false
end

# 2.
def exist_in_search_path_2?(file, paths)
  paths.split(":").reduce(false) { |r, dir|
    r |= FileTest.exist?(File.expand_path(file, dir))
  }
end

# 3.
def exist_in_search_path_3?(file, paths)
  result = paths.split(":").map { |d| File.expand_path(file, d) }.find { |p|
    FileTest.exist?(p)
  }
  !result.nil?
end

[:exist_in_search_path_1?, :exist_in_search_path_2?, :exist_in_search_path_3?].each { |m|
  puts send(m, "cat", ENV["PATH"])
  puts send(m, "catwoman", ENV["PATH"])
  puts send(m, "bat", ENV["PATH"])
  puts send(m, "batman", ENV["PATH"])
}

# I like 2.  However, it is wasteful.
# 1 is the most efficient way, I think.