(define-module (xxx mmr)
  #:export (->sql2))

(define-syntax ->
  (syntax-rules (end)
    ((_ end fmt args ...)
     (format #f "address@hidden;" fmt args ...))
    ((_ fmt args ...)
     (format #f fmt args ...))))

(define-syntax-rule (->end name arg)
  (-> end "~a ~a" name arg))

(define-syntax sql-alter
  (syntax-rules (table rename to add modify drop column as select
                 primary key)
    ((_ table name drop primary key)
     (-> "table ~a drop primary key" name))
    ((_ table old-name rename to new-name)
     (-> "table ~a rename to ~a" old-name new-name))
    ((_ table name add cname ctype) 
     ;; e.g: (->sql alter table 'mmr add 'cname 'varchar(50))
     (-> "table ~a add ~a ~a" cname ctype))
    ((_ table name mofify pairs)
     (-> "table ~a modify (~{~a~^,~})" name (->lst pairs)))
    ((_ table name drop column cname)
     (-> "table ~a drop column ~a" name cname))
    ((_ table name add primary key keys)
     (-> "table ~a add primary key (~{~a~^,~})" name keys))
    ((_ table name rename column old-name to new-name)
     (-> "table ~a rename column ~a to ~a" name old-name new-name))))

(define-syntax ->sql2
  (syntax-rules (select insert alter create update delete use)
    ((_ alter rest ...)
     (->end 'alter (sql-alter rest ...)))))