;======== ; Fall 2026 - CS 111 ; Week 6 Lab Exercise - save as lab6.rkt ; ; date: 2026-10-02 ;======== ;----- ; this file will use definitions and functions from these modules: (require 2htdp/image) (require 2htdp/universe) ;************* ; *** NOTE *** ; This lab has even MORE explanations than ; usual! Look for ;*** DO THIS *** ; ...right before the parts YOU are to add. ;======== ; also NOTE: ; * To receive credit for this lab exercise, you must: ; * be present during your lab section, ; either in BSS 313 or in the lab Zoom session, ; based on your lab section ; * participate appropriately in a pair, ; either in BSS 313 or in a Zoom breakout room ; ;======== ; USING pair-programming: ; 1. COPY and PASTE the contents of this ; file into a DrRacket Definitions window, and save as: ; ; lab6.rkt ; ; 2. ADD comments and expressions TO THIS as specified below ; (one student saying what to type, the other student typing it ; into DrRacket) ; ; ******** ; * DO NOT DELETE THE COMMENTS! They speed up grading! ; ******** ; ; ******** ; * DO NOT change or remove the string expressions ; already included to act as labels! ; ******** ; ; * remember: it is a class style standard to put a ; BLANK LINE between each comment-block and an expression ; following it ; ; 3. SAVE the contents of your definitions window frequently ; as you are working, to the driver's Google Drive, ; using a file name of lab6.rkt. ; ; 4. RUN the resulting file frequently as you are working, ; fixing any errors that arise. ; ; 5. When you are done, use Gmail to MAIL a copy of the ; resulting filled-in lab6.rkt file ; ; *** AS WELL AS YOUR PROGRAM-CREATED FILE practice.txt ***, ; ; to BOTH of you. ; ; 6. And, EACH of you should SUBMIT these TWO files, ; ; *** lab6.rkt AND practice.txt ***, ; ; to Canvas BEFORE you leave lab. ; ; 7. REMEMBER to also answer the ; "Week 6 Lab Exercise - Pair-Programming Peer Review Survey" ; in Canvas, posted along with this lab exercise, by ; 11:59 pm TONIGHT (Friday, October 2) ;======== ;*** DO THIS *** ;===== ; Leave a blank line, and then put COMMENT(s) containing BOTH ; of your names (include first AND last names) ;======== ; PROBLEM 1 - trying out some file input/output ;======== ; this expression lets you use DrRacket's file input/output ; functions, especially useful for ; "batch"-style programs (require 2htdp/batch-io) ;----- ; 1 part a ;----- ; REMINDER: you can say that you want a ; newline character in a Racket string by ; writing it as "\n" ;----- ; Consider the following signature and ; purpose comment for function write-file, ; from 2htdp/batch-io: ;======== ; signature: write-file: string string -> string ; purpose: expects the name of a file ; written as a string ; AND the string to write to that file, ; ; has the SIDE-EFFECT of trying to ; write that string to that ; file (creating that file if necessary), ; ; and returns the name of the file "" "should see the name of the file written:" "----------------------------------------" ;*** DO THIS *** ;----- ; WRITE an expression, using write-file, whose ; side-effects should be: ; * to create a file named practice.txt ; ; * that contains AT LEAST FIVE lines ; of contents of your choice, ; ; * making sure that AT LEAST TWO lines ; contain MORE THAN ONE WORD each. ;----- ; 1 part b ;----- ; Consider the following signature and ; purpose comment for function read-file, ; from 2htdp/batch-io: ;======== ; signature: read-file: string -> string ; purpose: expects the name of a file ; written as a string, ; ; has the SIDE-EFFECT of trying to ; open that file and read its contents, ; ; then returns the contents read as ; a single string "" "practice.txt contents as a SINGLE string:" "----------------------------------------" ;*** DO THIS *** ;----- ; WRITE an expression, using read-file, ; whose value will be a SINGLE string ; containing all of the contents ; of practice.txt: ;----- ; 1 part c ;----- ; Consider the following signature and ; purpose comment for function read-lines, ; from 2htdp/batch-io: ;======== ; signature: read-lines: string -> list ; purpose: expects the name of a file ; written as a string, ; ; has the SIDE-EFFECT of trying to ; open and read the contents of that file, ; ; and returns the read contents as a ; LIST of strings, each line being one ; string in the list "" "practice.txt contents as a list of " " line-strings:" "----------------------------------------" ;*** DO THIS *** ;----- ; WRITE an expression, using read-lines, ; whose value will be a LIST of strings, ; such that each string is ONE ; line from practice.txt: ;----- ; 1 part d ;----- ; Consider the following signature and ; purpose comment for function read-words, ; from 2htdp/batch-io: ;======== ; signature: read-words: string -> list ; purpose: expects the name of a file ; written as a string, ; ; has the SIDE-EFFECT of trying to ; open and read the contents of that file, ; ; and returns those contents as a list ; of strings, with each ; white-space-separated "chunk" being a ; string in this list "" "practice.txt contents as a list of" " word-strings:" "----------------------------------------" ;*** DO THIS *** ;----- ; WRITE an expression, using read-words, ; whose value will again be a LIST of ; strings -- but THIS time, each string ; will be one white-space-separated ; "WORD"/chunk from practice.txt: ;----- ; 1 part e ;----- ; Consider the following signature and ; purpose comment for function ; read-words/line, from 2htdp/batch-io: ;======== ; signature: read-words/line: string -> list ; purpose: expects the name of a file ; written as a string, ; ; has the SIDE-EFFECT of trying to open ; and read the contents of that file, ; ; and returns its contents as a list of ; lists, one sub-list per line, with ; the white-space-separated ; "words"/chunks in that line as ; strings in that line's list "" "practice.txt contents as a list of " " line-lists of word-strings:" "----------------------------------------" ;*** DO THIS *** ;----- ; WRITE an expression, using read-words/line, ; whose value will be a LIST of LISTS of ; strings -- such that each sub-list is ; a list of white-space-separated ; "WORD"/chunk strings from one line ; from practice.txt: ;======== ; PROBLEM 2 - writing a function that ; "walks through" a list ;======== ;==== TEMPLATE for a function that needs ; to "walk through" all of the elements of a ; variable-length list ; ; (define (a-list-funct ... a-list ...) ; (cond ; [(empty? a-list) ...] ; [else (... ; ... (first a-list) ... ; (a-list-funct ... (rest a-list) ...) ...) ; ] ; ) ; ) ;*** DO THIS *** ;-------- ; Using the DESIGN RECIPE, design a function ; sum-list, which expects a list of numbers, ; and just returns the SUM of the numbers in ; that list. If called with an empty list, ; it should return 0. ; ; * That is, if this function has as ; its argument a list of numbers ; containing 7, 10, and 41, then it ; would return 58. ; ; Amongst its tests, include at least: ; * one whose argument is an empty list ; * one whose argument is a list of three or more numbers ;===== ; Remember: once you have Run these and are satisfied ; with them, ; * Use Gmail to EMAIL copies of this file lab6.rkt ; *** AND ALSO YOUR FILE practice.txt ***, ; to BOTH of you ; ; * BOTH of you should submit this file ; *** AND ALSO YOUR FILE practice.txt *** ; to Canvas BEFORE you leave lab. ; ; * ALSO answer the ; "Week 6 Lab Exercise - Pair-Programming Peer Review Survey" ; in Canvas, posted along with this lab exercise, by ; 11:59 pm TONIGHT (Friday, October 2) ;=====