ExprOrBlock = (EQ Expr | Block)

typedef Name EQ Type
const Name EQ Expr

fun Name (L ArgList R)[: Type] [LSQ LocalList RSQ] BlockOrExpr2D : Stmt
do (I ArgList I) | (ArgList.) BlockOrExprNoEQ2D : Expr

loop(L Name R) [(while | until) Expr] Block : Stmt
break(L Name R) : Expr
continue(L Name R) : Expr

WhenBr = when LB { Expr => Expr }  [else => Expr] RB
  | when NL l:Layout Expr (l Expr)*
WhenInfix = when Expr LB {infix Expr => Expr} [else => Expr] RB | {- 2D part -}
WhenEq = when Expr LB { Expr => Expr } [else => Expr] | {- 2D part -}
When: Expr = WhenBr, WhenInfix, WhenEQ

Var = var Name : Expr
Call = Name (L Args R) [ Block ] : Expr
Infix = Expr infix Expr : Expr {- 大意，因为分 infixl/infixr - }

(=) (+) (-) (*) (/) (mod)
(>) (>=) (<) (<=) (==) (!=)

#bulk.rb

def bulkRename(re_src, pat_dst, fmt_dst)
  re_dst = Regexp.new(pat_dst)
  selected = Dir.glob(re_src)
  for name in selected
    newnam = name.gsub(re_dst, fmt_dst)
    puts("mv #{name} #{newnam}")
    File.rename(name, newnam)
  end 
end  

case ARGV.size # Just br size is OK
  when 0 then warn("Usage: #{$0} [select] re_dst fmt_dst")
  when 1 then puts(Dir.glob($*[0]))
  when 2 then bulkRename('*', $*[0], $*[1])  
  when 3 then bulkRename($*[0], $*[1], $*[2])
end

#move_back.rb
for ln in $<.each_line do
  next unless ln.start_with?('mv')
  _mv, src, dst = ln.split
  puts("mv #{dst} #{src}")
end