Talk I gave about Contracts vs Types

slides.rkt

#lang slideshow
(require slideshow/code)

(set-margin! 20)
(current-font-size 36) ; default is 32

(slide
 #:title "My Perspective"
 (item "A long-time fan of static types")
 (item "Respect that very good programmers disagree")
 (item "Liking contracts now due to recent Racket project"))

(slide
 #:title "A Basic Contract in Racket"
 (typeset-code
  #'(begin
      (define amount?
        (and/c number? positive?))
      (define/contract (deposit account amount)
        (-> account? amount? account?)
        (error "not implemented"))))
 (item "This is an unambiguous notation")
 (item "That matches the code"))

(slide
 #:title "Static Typing Benefits"
 (item "Helps me understand code as I'm writing it")
 'next
 (item "Helps me understand the original author's intent")
 'next
 (item "Helps me reason about the code")
 'next
 (item "Ensures a minimum level of documentation and code quality")
 'next
 (item (it "Contracts work just as well for these things!")))

(slide
 #:title "Static Typing Benefits"
 (item "Helps me refactor or modify existing code")
 'next
 (item "Exploring the impact of a potential code change")
 'next
 (item (it "Contracts work depending on your test coverage")))

(slide
 #:title "Static Typing Pains"
 (item "Can be tedious to prove things to the type checker")
 'next
 (item "Requires the entire program to type check"))

(slide
 #:title "Conclusion"
 (item "Static Typing and Contracts solve a lot of the same problems")
 (item "Each has its own strengths and weaknesses, but these differences seem minor now"))