letrecとdisplay closureの関係になやむ

letrecとdisplay closureの関係になやむ。
Gauche のcompile.scmにおける letrec の扱いを読んでみるか。

;; LOCAL-ENV-CLOSURES(nlocals) <codelist>
;;  Used for letrec.
;;  Similar to LOCAL-ENV, but this doesn't use the current arg frame.
;;  The operand contains a literal list of compiled codes.  This instruction
;;  creates a frame of NLOCALS size, then creates closures
;;  with the new environment and the given compiled codes, and fills the
;;  new frame with the created closures.   CODELIST can have 'holes', i.e.
;;  if it has #f instead of a compiled code, the corresponding frame entry
;;  is left undefined.
;;  This instruction also leaves the last closure in VAL0.