;; The first three lines of this file were inserted by DrRacket. They record metadata
;; about the language level of this file in a form that our tools can easily process.
#reader(lib "htdp-beginner-reader.ss" "lang")((modname lect06) (read-case-sensitive #t) (teachpacks ()) (htdp-settings #(#t constructor repeating-decimal #f #t none #f ())))
;; What is the *type* (the "signature") of:

; (a) string-ref
(string-ref "howdy" 2)

; (b) number->string
(number->string (sqrt 144.0))

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#| The Design Recipe (take 1 -- primitive types only)

  ------- per function:
    4. tests
    5. stub : signature, head, description, body
    7. complete the body-expression
    8. watch your tests pass
|#



; Let's write "monogram":
; Given somebody's name, make a monogram (three letters) for them.
; (Might be used at bottom of business letters, or on fancy towels.)