CSC153, Class 18: More Higher-Order Procedures

Overview:
* Operator Sections
* Currying
* Lab
* Reflection

Notes:
* About Produces and Postconditions
* More questions on exam 1?
* Read Bailey
* Comments on Mr. Stone's book?
* Making Delete work the way you want
* HW1 graded.  Writeup 2 not graded.

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Defining procedures

(define name
  (lambda (param1 ... paramn)
     body))

(define (name param1 ... paramn)
  body)
  
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Operator Sections:
* Observation: We often want to fill in some of the
  parameters to a procedure, but not all of them.
"Whoops, I really should add 10 to everyone's grade on the
 exam"
(map "add 10" list-of-grades)
(map (lambda (x) (+ 10 x)) list-of-grades)

(define left-section 
  (lambda (binary-procedure first-param)
    (lambda (second-param)
      (binary-procedure first-param second-param))))

(map (left-section + 10) list-of-grades)

(define add10 (left-section + 10))

REMINDER: Explain cute

If generalization is your cup of tea, you might want to
define a variant of left-section that takes an N-ary procedurea
and M of its parameters, and returns an (N-M)-ary procedure

This generalization is cute.

(cute NAME_OF_PROCEDURE filled-in-argument <> ...)

(define add10 (cute + 10 <>))

(define sub5 (cute - <> 5))

(define square-list (cute map (lambda (x) (* x x)) <>))

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Currying: We'll discuss it later.

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Reflection:

For right-insert, your base case should be "does the list have 
only one element" and not "does the list have no elements"