* Flatbind

The =flatbind= system exports a single symbol called =do>=, which is a
DSL that is a kind of gross mutant of =let*= and
=alexandria:when-let*=, with some =multiple-value-bind= and
=with-slots= and =destructuring-bind= mixed in.

It was built with [[https://cicadas.surf/cgit/colin/argot.git/about/][argot]]


** Example

#+begin_src lisp

(do>
  object :when= (get-some-oject)
  (x y) :slots= object
  :when (evenp (+ x y))
  :when (plusp y)
  (quotient remainder) := (floor (+ x y) y)
  (newx newy &key message) :match= (calculate-new-x-y quotient remainder)
  (setf x newx ;; X and Y were bound above like WITH-SLOTS
        y newy)
  (print message))

#+end_src



** Grammar
#+begin_verse
FLATBIND:DO>
  [symbol]

DO> names a macro:
  Lambda-list: (&BODY TOKENS)
  Documentation:
    
    
    start           ::= clause* eof
    clause          ::= (binding-clause | destructuring-clause | with-slots-clause | predicate-binding-clause | predicate-clause | simple-clause)
    binding-clause  ::= values-bind ':=' token
    values-bind     ::= token
    destructuring-clause ::= destructuring-list ':MATCH=' token
    destructuring-list ::= token
    with-slots-clause ::= slot-value-list ':SLOTS=' token
    slot-value-list ::= token
    predicate-binding-clause ::= token ':WHEN=' token
    predicate-clause ::= ':WHEN' token
    simple-clause   ::= token
    ------------------------------------------
    ADDITIONAL NOTES:
    values-bind       Either a symbol or a list suitable for passing to MULTIPLE-VALUE-BIND
    destructuring-list   An list that might be passed as the first argument to DESTRUCTURING-BIND.
    slot-value-list   A list that is suitable for passing to with-slots.
    predicate-binding-clause   Bind variable to form, exit early if form evaluated to nil.
    ------------------------------------------
    KEY: 
    token      Any ole token
    eof        Explicitly match the end of the input
    {LANGUAGE} Parse a sublist of tokens with LANGUAGE
    (A|B|...)  One of the alternavites a b ...
    PATTERN+   One or more PATTERN
    PATTERN*   Zero or more PATTERN
    OPT?       Zero or one of OPT
  Source file: /home/colin/projects/flatbind/flatbind.lisp

Symbol-plist:
  ARGOT::GRAMMAR-PROPERTY -> #<ARGOT::GRAMMAR {100B8F0433}>
#+end_verse