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- Committer: Rodolfo Carvalho
- Date: 2011-05-17 02:42:05 UTC
- Revision ID: rhcarvalho@gmail.com-20110517024205-7p155j135ytm77h3
Intro do Racket as taken from the web
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removed
intro-to-racket/racket-lecture.rkt
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#lang slideshow
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(require slideshow/code)
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(require scheme/pretty)
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(require (file "compile.rkt"))
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;; Library.
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(define (large-text txt)
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(text txt (current-main-font) 62))
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(define (pretty-syntax sexp . cols)
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(let ((port (open-input-string (apply pretty-format (cons sexp cols)))))
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(port-count-lines! port)
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(read-syntax "<no-name>" port)))
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(define-syntax code-reduce
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(syntax-rules ()
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((_ exp)
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(let ((t exp))
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(hb-append (code exp) (tt " => ") (code (unsyntax t)))))))
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(define comma ", ")
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(define (fact n)
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(cond
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((<= n 0) 1)
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(else (* n (fact (- n 1))))))
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;; Slides.
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(slide
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(para #:align 'center
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(large-text "Introduction to Racket"))
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(blank 50)
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(vc-append 0
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(t "Matthew Might")
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(colorize (bt "University of Utah") "red")
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(colorize (t "matt.might.net") "blue")))
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(slide
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#:title "Why learn Racket (or Lisp)?"
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(para #:align 'center #:width 500
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"A good FORTRAN programmer can write FORTRAN in any language.")
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(blank 75)
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'next
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(para #:align 'center #:width 450 "A good Lisp programmer can write any language in Lisp.")
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)
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(slide
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#:title "Why learn Racket (or Lisp)?"
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(para #:align 'center #:width 400
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"A good C programmer can write C in any language.")
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(blank 75)
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(para #:align 'center #:width 450 "A good Racket programmer can write any language in Racket.")
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)
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(slide
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#:title "What is Racket?"
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(item "Lisp is λ-calculus done right.")
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(item "Scheme is Lisp done right.")
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(item "Racket is Scheme done right."))
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(slide
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#:title "Origins of Scheme: Lisp"
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#:layout 'center
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(ht-append
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(vc-append
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(scale (bitmap "jmcbw.jpg") 0.5)
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(t "John McCarthy"))
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(vl-append
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(item #:width 200 (t "Lisp created in 1958"))
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(item #:width 200 (t "Based on λ-calculus"))
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(item #:width 200 (t "Based on list-processing"))
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(item #:width 200 (t "S-Expression syntax"))
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(item #:width 200 (t "Code acts as data"))
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(item #:width 200 (t "Data acts as code"))
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)))
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(slide
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#:title "Core S-Expression syntax"
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(tt "<s-exp> ::= <symbol> ")
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(tt " | (<s-exp> ...)"))
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(slide
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#:title "S-Expressions: Benefits"
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(vl-append
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30
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(blank 100)
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(item #:width 200 "Human-readable")
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(item #:width 200 "Human-writable")
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(item #:width 200 "Easy to parse")))
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(slide
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#:title "S-Expression example"
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(vl-append
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0
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(tt "(ships ")
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(tt " (ship (name Enterprise)")
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(tt " (x 120) ")
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(tt " (y 150)) ")
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(tt " (ship (name Galactica) ")
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(tt " (x 130) ")
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(tt " (y 42))) ")))
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(slide
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#:title "XML: High-calorie S-Expressions"
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(vl-append
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0
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(tt "<ships>")
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(tt " <ship>")
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(tt " <name>Enterprise</name>")
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(tt " <x>120</x>")
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(tt " <y>150</y>")
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(tt " </ship>")
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(tt " <ship>")
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(tt " <name>Galactica</name>")
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(tt " <x>130</x>")
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(tt " <y>42</y>")
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(tt " </ship>")
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(tt "</ships>")
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))
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(slide
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#:title "S-Expressions: Universal syntax"
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(vl-append
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0
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(tt "class Dog extends Pet {")
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(tt " void bark() { ")
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(tt " print(\"woof\") ; ")
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(tt "}}"))
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'next
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'alts
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(list
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(list (vl-append
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0
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(tt "(class Dog extends Pet")
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(tt " (void (bark) ")
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(tt " (print \"woof\")))")))
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(list (vl-append
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0
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(tt "(class")
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(tt " (name Dog)")
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(tt " (extends Pet)")
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(tt " (methods ")
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(tt " (method ")
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(tt " (name bark)")
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(tt " (args ())")
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(tt " (type (-> () void)) ")
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(tt " (body (print \"woof\"))))))")))))
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(slide
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#:title "Scheme"
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#:layout 'center
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(ht-append
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50
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(vc-append
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(bitmap "steele.jpg")
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(t "Guy Steele"))
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(vl-append
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(item #:width 200 (t "Lisp done right, 1978"))
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(item #:width 200 (t "Fixed scoping oversight"))
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(item #:width 200 (t "Purified formal semantics"))
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(item #:width 200 (t "Hygienic macro system"))
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)))
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(slide
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#:title "Racket"
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#:layout 'center
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(ht-append
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(vc-append
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(bitmap "matthew.jpg")
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(t "Matthew Flatt"))
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(vl-append
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(item #:width 200 (t "Scheme done right, 2010"))
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(item #:width 200 (t "Added huge library system"))
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(item #:width 200 (t "Adds modules, structs, etc."))
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(item #:width 200 (t "Batteries included"))
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)))
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(slide
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#:title "Racket example: Factorial"
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(code
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(define (fact n)
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(cond
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((<= n 0) 1)
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(else (* n (fact (- n 1))))))))
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(slide
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#:title "Racket programs"
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(tt "<body> ::= <def> ... <exp> ..."))
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(slide
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#:title "Definitions"
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(vl-append
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(tt "<def> ::= (define (<id> <params>) <body>)")
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(tt " | (define <id> <exp>)")))
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(define (id x) x)
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(define (subset-scheme-slide show-core show-global show-basic show-sugar)
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(slide
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#:title "A subset of Scheme expressions"
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(vl-append
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(tt "<exp> ::= <var>")
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(show-basic (tt " | <num>"))
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(show-basic (tt " | <prim>"))
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(show-basic (tt " | <bool>"))
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(blank 15)
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(show-core (tt " | (<exp> <exp> ...)"))
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(show-core (tt " | (λ (<params>) <body>)"))
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(blank 15)
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(show-basic (tt " | (if <exp> <exp> <exp>)"))
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(show-sugar (tt " | (cond (<exp> <exp>) ...)"))
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(blank 15)
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(show-sugar (tt " | (let ((<var> <exp>) ...) <body>)"))
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(show-sugar (tt " | (let* ((<var> <exp>) ...) <body>)"))
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(show-sugar (tt " | (letrec ((<var> <exp>) ...) <body>)"))
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(blank 15)
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(show-sugar (tt " | (quote <sexp>)"))
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(show-sugar (tt " | (quasiquote <qq-sexp>)"))
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(blank 15)
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(show-global (tt " | (begin <body>)"))
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(show-global (tt " | (set! <var> <exp>)"))
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)))
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;(subset-scheme-slide id id id id)
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;(subset-scheme-slide id id id ghost)
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;(subset-scheme-slide id id ghost ghost)
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;(subset-scheme-slide id ghost ghost ghost)
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(slide
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(large-text "A tour of Racket"))
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(slide
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#:title "Numbers"
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(item "Integers: " (code 1) "," (code -3))
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(item "Rationals: " (code-reduce (/ 8 10)))
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(item "\"Reals\": " (code-reduce (sqrt 2)))
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(item "Imaginary: " (code-reduce (sqrt -1)))
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(item "Complex: " (code-reduce (* 1+3i 1-22/7i)))
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(item "Precise: " (code-reduce (fact 18))))
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(slide
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#:title "Booleans"
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(item "Boolean literals " (code #t) ", " (code #f))
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(item "Only " (code #f) " is false")
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(item "Anything else is true")
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)
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(slide
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#:title "Lists"
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(item (code cons) ", " (code car) ", " (code cdr) ", " (code '())
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", " (code pair?))
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'next
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(item (code-reduce (cons 1 '())))
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'next
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(item (code-reduce (cons 3 (cons 1 '()))))
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'next
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(item (code-reduce '(3 1)))
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'next
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(item (code-reduce (car (cons 3 (cons 1 '())))))
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'next
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(item (code-reduce (cdr (cons 3 (cons 1 '())))))
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'next
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(item (code-reduce (pair? (cons 3 4))))
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'next
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(item (code-reduce (null? '())))
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)
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(slide
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#:title "Quoted S-Expressions"
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(item (code '<s-exp>) (tt " == ") (tt "(quote <s-exp>)"))
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(item (code-reduce '<id>))
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(item (code-reduce '3))
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(item (code-reduce 'a))
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(item (code-reduce '(1 2 3)))
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(item (code-reduce (cdr '(1 2 3))))
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(item (code-reduce '(f (g x))))
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(item (code-reduce (car '(f (g x)))))
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(item (code-reduce '())))
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(slide
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#:title "Primitives"
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(item "Arithmetic: " (code +) ", " (code modulo) ", " (code quotient))
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(item "Types: " (code null?) ", " (code pair?) ", " (code number?) ", " (code integer?))
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(item "Lists: " (code list) comma (code cons) ", " (code car)", " (code cdr))
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(item "Equality: " (code =)", " (code eq?)", " (code eqv?) comma (code equal?))
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(item "Ex:" (code-reduce (gcd 248 184)))
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(item "Ex:" (code-reduce (cons 3 (cons 4 '()))))
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)
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(slide
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#:title (code let)
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(item (para #:width 200 #:align 'left
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(tt "<let-exp> ::= ")
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(tt " (let ((<var> <exp>) ...) ")
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(tt " <body>)")))
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(item (code let) " binds values to variable names")
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'next
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(item (code-reduce (let ((π 3.14)
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(two 2))
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(* two π))))
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'next
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(item (code (let ((π 3.14)
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(2*π (* 2 π)))
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2*π)) (colorize (tt " =/=> ") "red") (code 6.28)))
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(slide
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#:title (code let*)
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(item (para #:width 200 #:align 'left
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(tt "<let*-exp> ::= ")
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(tt " (let* ((<var> <exp>) ...) ")
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(tt " <body>)")))
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(item (code let*) " binds values to variable names sequentially")
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'next
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(item (code-reduce (let* ((π 3.14)
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(π 3.14159))
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(* 2 π))))
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'next
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(item (code-reduce (let* ((π 3.14)
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(2*π (* 2 π)))
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2*π))))
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(slide
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#:title "Variables"
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(item "Any symbol allowed")
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(item "Roughly: " (tt "[^()'`,]+"))
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(item "Ex:" (code foo))
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(item "Ex:" (code foo-bar))
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(item "Ex:" (code π) comma (code Δ) comma (code ∞) comma (code Σ) comma (code ⊑) comma (code ∅) comma (code →))
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(item "Ex:" (code pair?))
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(item "Ex:" (code call-with-current-continuation))
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(item "Ex:" (code-reduce (let ((let 3)) let))))
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(slide
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#:title "λ"
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(item "λ produces anonymous functions")
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(item (tt "<lambda> ::= (λ (<var> ...) <body>)"))
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; (item (tt "<params> ::= <var> ..."))
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(item (code-reduce ((λ (x) (* x x)) 3)))
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(item (code (let ((λ (λ (λ) (λ λ)))) (λ λ)))))
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(slide
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#:title "Lexical scope"
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(t "To what does the following evaluate?")
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(blank)
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(code
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(let ((x 20))
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(let* ((x 3)
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(f (λ () x))
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(x 10))
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(f)))))
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(slide
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#:title "Lexical scope"
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(item "λ-terms capture bindings in scope")
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(item "WYSIWYG for anonymous functions"))
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(slide
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#:title "Obligatory derivative example"
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(code
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(define ε 0.001)
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(define (D f) (λ (x) (/ (- (f (+ x ε)) (f x))
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ε)))
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(define (g x) (* x x))
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((D g) 0) ≈ 0
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((D g) 2) ≈ 4))
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(slide
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#:title "Conditionals"
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(item (tt "<if-exp> ::= (if <exp> <exp> <exp>)"))
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(item (tt "<cond-exp> ::= ") (tt " (cond (<exp> <exp>) ...)"))
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(item (code-reduce (if 'a 'b 'c)))
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(item (code-reduce (if #f 'b 'c)))
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(item (code-reduce (cond
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((< 3 0) 'negative)
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((= 3 0) 'zero)
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((> 3 0) 'positive)))))
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(slide
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#:title "Quasiquotes"
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(item "Special syntax for constructing literals")
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(item (tt "`<qq-sexp>") (tt " == ") (tt "(quasiquote <qq-sexp>)"))
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(item (tt ",<exp>") (tt " == ") (tt "(unquote <exp>)"))
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(item (code-reduce `(3 + 4 is ,(+ 3 4))))
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(code
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(let ((new-ship (λ (name x y)
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`(ship (name ,name)
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(x ,x)
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(y ,y)))))
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(new-ship 'Enterprise 42 1701)))
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'next
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(code => (ship (name Enteprise)
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(x 42)
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(y 1701))))
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(slide
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#:title "Mutating variables"
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(item (code begin) " sequences expressions, like " (tt "{}") " in C")
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(code-reduce
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(begin
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1
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2
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3))
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(item (code set!) " assigns to a variable, like " (tt "=") " in C")
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(code-reduce
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(let ((π 3.14))
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(begin
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(set! π 3.14159)
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π)))
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)
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(slide
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#:title "Pattern-matching"
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(item "Powerful tool for dissecting data like trees")
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'next
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(code-reduce
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(match '(1 2 3)
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[`(1 ,x 4) x]
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[`(1 2 ,z) z]))
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'next
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(code-reduce
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(match '(1 3 5 9)
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[(list 1 (? even?) ...)
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'all-even]
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[(list 1 (? odd?) ...)
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'all-odd])))
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