An implementation of letrec

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Introduction to Functional Programming in Scheme - slide 42 : 49

An implementation of letrec

letrec can be implemented with use of an assignment

 
(letrec ((n<sub>1</sub> e<sub>1</sub>)
         ...
         (n<sub>k</sub> e<sub>k</sub>))
    body-expr)

 
(let ((n<sub>1</sub> #f)
      ...
      (n<sub>k</sub> #f))
   (set! n<sub>1</sub> e<sub>1</sub>)
   ...
   (set! n<sub>k</sub> e<sub>k</sub>)
   body-expr)