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‎www/assignments.scrbl‎

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@include-section{assignments/2.scrbl}
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@include-section{assignments/3.scrbl}
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@include-section{assignments/4.scrbl}
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@include-section{assignments/5.scrbl}

‎www/assignments/5.scrbl‎

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#lang scribble/manual
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@title[#:tag "Assignment 5" #:style 'unnumbered]{Assignment 5: A Heap of Characters}
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@(require (for-label (except-in racket ...)))
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@(require "../notes/fraud-plus/semantics.rkt")
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@(require redex/pict)
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@(require "../notes/ev.rkt")
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@bold{Due: Thurs, Oct 3, 11:59PM}
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@(define repo "https://classroom.github.com/a/Qsw0mqpL")
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The goal of this assignment is to extend a compiler with data types
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that require memory allocation and dereferencing.
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Assignment repository:
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@centered{@link[repo repo]}
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You are given a repository with a starter compiler similar to the
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@seclink["Hustle"]{Hustle} language we studied in class. You are tasked
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with:
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@itemlist[
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@item{incorporating the Fraud+ features you added in
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@seclink["Assignment 4"]{Assignment 4},}
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@item{extending the language to include a string data type,}
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@item{implementing a number of primitives,}
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@item{updating the parser to work for Hustle+.}
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]
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@section[#:tag-prefix "a5-" #:style 'unnumbered]{From Fraud+ to Hustle+}
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Implement all the features of Fraud+, extended to Hustle+.
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@section[#:tag-prefix "a5-" #:style 'unnumbered]{Strung out}
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In the last assignment, you implemented a character data type for
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representing single letters. In this assignment, you will implement a
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String data type for representing arbitrarily long sequences of
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characters.
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Strings are disjoint from all other data types and are essentially a
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fixed-size array of characters. Literal strings are written by
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enclosing the characters within the string in double quotes (@tt{"}).
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Strings can include double quotes by using the escape sequence
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@tt{\"}.
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You must add the following operations to Hustle+:
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@itemlist[
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@item{@code[#:lang "racket"]{string? ; Any -> Boolean}, which determines if its argument is a string.}
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@item{@code[#:lang "racket"]{string-ref ; String Natural -> Char}, which
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extracts the character at the given index (using 0-based counting). An error is signalled if
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the index is out of bounds for the given string.}
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@item{@code[#:lang "racket"]{string-length ; String -> Natural}, which computes the length of the string.}
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@item{@code[#:lang "racket"]{make-string ; Natural Char -> Natural}, which constructs a string of the given
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length, filled with the given character.}
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]
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The run-time system has been updated to account for a string type. It
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assumes a representation where the length of the string is stored in
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memory, followed by the characters of the string, in order. You are
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free to change the representation if you'd like, but you will have to
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update the run-time system to properly print strings. Otherwise, no
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changes to the run-time system should be necessary.
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@section[#:tag-prefix "a5-" #:style 'unnumbered]{More operations}
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Add the following operations to the Hustle+ language:
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@itemize[
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@item{@code[#:lang "racket"]{box? ; Any -> Boolean}, which determines
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if a value is a box.}
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@item{@code[#:lang "racket"]{empty? ; Any -> Boolean}, which
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determines if a value is the empty list.}
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@item{@code[#:lang "racket"]{cons? ; Any -> Boolean}, which determines
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if a value is a pair.}
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@item{@code[#:lang "racket"]{= ; Number Number -> Boolean}, which determines if
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two numbers are equal.}
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@item{@code[#:lang "racket"]{< ; Number Number -> Boolean}, which determines if
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the first number is less than the second.}
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@item{@code[#:lang "racket"]{<= ; Number Number -> Boolean}, which determines if
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the first number is less than or equal to the second.}
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@item{@code[#:lang "racket"]{char=? ; Number Number -> Boolean}, which determines if
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two characters are equal.}
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@item{@code[#:lang "racket"]{boolean=? ; Boolean Boolean -> Boolean}, which determines if
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two booleans are equal.}
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]
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@section[#:tag-prefix "a5-" #:style 'unnumbered]{Extending your Parser, yet again!}
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Extend your Fraud+ parser for the Hustle+ language based on the following
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grammar:
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@verbatim{
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<expr> ::= integer
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| character
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| boolean
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| variable
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| string
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| ( <compound> )
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| [ <compound> ]
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<compound> ::= <prim1> <expr>
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| <prim2> <expr> <expr>
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| if <expr> <expr> <expr>
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| cond <clause>* <else>
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| let <bindings> <expr>
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<prim1> ::= add1 | sub1 | abs | - | zero? | integer->char | char->integer
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| char? | integer? | boolean? | string? | box? | empty? | cons?
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| box | unbox | car | cdr | string-length
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<prim2> ::= make-string | string-ref | = | < | <=
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| char=? | boolean=? | +
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<clause> ::= ( <expr> <expr> )
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| [ <expr> <expr> ]
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<else> ::= ( else <expr> )
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| [ else <expr> ]
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<bindings> ::= ( <binding>* )
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| [ <binding>* ]
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<binding> ::= ( variable <expr> )
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| [ variable <expr> ]
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}
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There is a lexer given to you in @tt{lex.rkt}, which provides two
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functions: @racket[lex-string] and @racket[lex-port], which consume a
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string or an input port, respectively, and produce a list of tokens,
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which are defined as follows (only the new parts are shown):
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@#reader scribble/comment-reader
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(racketblock
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; type Token =
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; ...
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; | `(prim1 ,Prim1)
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; | `(prim2 ,Prim2)
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; | String
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; type Prim1 =
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; | 'add1
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; | 'sub1
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; | 'zero?
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; | 'abs
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; | '-
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; | 'integer->char
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; | 'char->integer
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; | 'char?
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; | 'boolean?
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; | 'integer?
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; | 'string?
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; | 'box?
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; | 'empty?
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; | 'cons?
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; | 'box
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; | 'unbox
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; | 'car
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; | 'cdr
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; | 'string-length
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; type Prim2 =
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; | 'make-string
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; | 'string-ref
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; | '=
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; | '<
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; | '<=
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; | 'char=?
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; | 'boolean=?
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; | '+
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; | '-
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)
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The lexer will take care of reading the @tt{#lang racket} header and
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remove any whitespace.
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You must complete the code in @tt{parse.rkt} to implement the parser
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which constructs an s-expression representing a valid Hustle+
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expression, if possible, from a list of tokens. The @racket[parse]
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function should have the following signature and must be provided by
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the module:
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@#reader scribble/comment-reader
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(racketblock
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;; parse : [Listof Token] -> Expr
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)
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As an example, @racket[parse] should produce @racket['(add1 (sub1 7))]
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if given
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@racketblock['(lparen (prim1 add1) lparen (prim1 sub1) 7 rparen rparen eof)]
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You should not need to make any changes to @tt{lex.rkt}.
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@section[#:tag-prefix "a5-" #:style 'unnumbered]{Testing}
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You can test your code in several ways:
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@itemlist[
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@item{Using the command line @tt{raco test .} from
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the directory containing the repository to test everything.}
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@item{Using the command line @tt{raco test <file>} to
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test only @tt{<file>}.}
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@item{Pushing to github. You can
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see test reports at:
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@centered{@link["https://travis-ci.com/cmsc430/"]{
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https://travis-ci.com/cmsc430/}}
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(You will need to be signed in in order see results for your private repo.)}]
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Note that only a small number of tests are given to you, so you should
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write additional test cases.
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@bold{There is separate a repository for tests!} The testing set-up
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is slightly different for this assignment. There is a whole other
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repository that contains tests. When you push your code, Travis will
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automatically run your code against the tests. If you would like to
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run the tests locally, clone the following repository into the
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directory that contains your compiler and run @tt{raco test .} to test
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everything:
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@centered{@tt{https://github.com/cmsc430/assign05-test.git}}
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This repository will evolve as the week goes on, but any time there's
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a significant update it will be announced on Piazza.
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@section[#:tag-prefix "a5-" #:style 'unnumbered]{Submitting}
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Pushing your local repository to github ``submits'' your work. We
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will grade the latest submission that occurs before the deadline.
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‎www/schedule.scrbl‎

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@secref["Hustle"])
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(list @wk{10/1}
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"A5" @;seclink["Assignment 5"]{A5}
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@seclink["Assignment 5"]{A5}
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@elem{TBD}
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'cont)
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