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CS3L: Introduction to Symbolic Programming

CS3L: Introduction to Symbolic Programming. Summer 2008 Colleen Lewis colleenL@berkeley.edu. Lecture 19: HOF Problems. Announcements. Midterm two Tuesday July 29 th This one will probably be harder than the first Colleen will be out of town Thurs-Monday Homework

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CS3L: Introduction to Symbolic Programming

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  1. CS3L: Introduction to Symbolic Programming Summer 2008 Colleen Lewis colleenL@berkeley.edu Lecture 19: HOF Problems

  2. Announcements • Midterm two Tuesday July 29th • This one will probably be harder than the first • Colleen will be out of town Thurs-Monday • Homework • Miniproject 3 started yesterday! • Due Friday July 25th at 11:59 pm • Today is Gilbert’s 7,000th day! And we’re having a surprise party for him!

  3. Today • Problem:Successive-concatenations • Which HOFs should I use? • Work on the mini-project • Let me know if you don’t have a partner and want one

  4. Successive Concatenations (sc '(a b c d e))  (a ab abc abcd abcde) (sc '(the big red barn))  (the thebig thebigred thebigredbarn) (define (sc sent) (accumulate (lambda ?? ) sent))

  5. Successive Concatenations (accumulate (lambda () …) ‘(the big red barn) ‘the  ‘(the thebig thebigred thebigredbarn) ‘big  ‘(big bigred bigredbarn) ‘red ‘barn  ‘(red redbarn)

  6. Successive Concatenations (accumulate (lambda () …) ‘(the big red barn) (lambda (new-wd so-far) (every (lambda (wd) (word new-wd wd)) (se “” so-far))) (proc ‘big ‘(red redbarn))  ‘(big bigred bigredbarn)

  7. Successive Concatenations (sc '(a b c d e))  (a ab abc abcd abcde) (sc '(the big red barn))  (the thebig thebigred thebigredbarn) (define (sc sent) (accumulate (lambda (new-wd so-far) (every (lambda (wd) (word new-wd wd)) (se “” so-far)) sent))

  8. accumulate (accumulateprocedure sent) • procedure • a procedure that takes in two arguments • a procedure that combines things together • sent • a sentence with 1 or more words • a word with 1 or more letters

  9. every (everyprocedure sent) • procedure • a procedure that takes in one argument • a procedure that returns a word or a sentence • sent • a sentence with 0 or more words • a word with 0 or more letters

  10. keep (keepprocedure sent) • procedure • a procedure that takes in one argument • a procedure that returns #t or #f • sent • a sentence with 0 or more words • a word with 0 or more letters

  11. Which HOFs would you use? • Capitalize-proper-names (c-p-n '(mr. smith goes to washington)) (mr. Smith goes to Washington) • Every • Keep • Accumulate

  12. Which HOFs would you use? • Longest Word (longest-word '(have a great week))  great • Every • Keep • Accumulate

  13. Which HOFs would you use? • Count-if odd? (count-if odd? '(1 2 3 4 5))  3 (count-if odd? '(1 2 3 4 2))  2 • Every • Keep • Accumulate

  14. Which HOFs would you use? • Count-vowels-in-each (c-v-i-e '(good luck on tuesday))  (2 1 1 3) • Every • Keep • Accumulate

  15. Which HOFs would you use? • Squares-greater-than-100 (s-g-t-100 '(2 9 13 16 9 45))  (169 256 2025) • Every • Keep • Accumulate

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