Revised assignment schedule, publish assign 5.

Author: dvanhorn

www/assignments.scrbl

@@ -12,7 +12,7 @@
 @include-section{assignments/7.scrbl}
 @include-section{assignments/8.scrbl}
 @include-section{assignments/9.scrbl}
-@include-section{assignments/10.scrbl}
+@;include-section{assignments/10.scrbl}
 
 
 @;{assignment 8: quote in general, and quasiquote}

www/assignments/5.scrbl

@@ -1,12 +1,106 @@
 #lang scribble/manual
 @(require "../defns.rkt")
-@title[#:tag "Assignment 5" #:style 'unnumbered]{Assignment 5: When and unless}
+@title[#:tag "Assignment 5" #:style 'unnumbered]{Assignment 5: Let There Be (Many) Variables}
 
 @(require (for-label a86/ast (except-in racket ...)))
 
 @bold{Due: @assign-deadline[5]}
 
-Details of this assignment will be released later in the semester.
+The goal of this assignment is to extend a compiler with binding forms
+that can take any number of arguments.
+
+@section[#:tag-prefix "a5-" #:style 'unnumbered]{Overview}
+
+For this assignment, you are given a @tt{fraud-plus.zip} file on ELMS
+with a starter compiler similar to the @seclink["Fraud"]{Fraud}
+language we studied in class.
+
+@section[#:tag-prefix "a5-" #:style 'unnumbered]{Fraud+}
+
+The Fraud+ language extends the Fraud language we studied in class with some
+new features:
+
+@itemlist[
+
+@item{The features added in @seclink["Assignment 4"]{Assignment 4}, namely:
+
+  @itemlist[
+
+  @item{@racket[abs], @racket[-], and @racket[not]}
+  @item{@racket[cond]}
+  @item{@racket[case]}
+
+  ]}
+
+@item{New primitives @racket[integer?] and @racket[boolean?].}
+
+@item{An extended @racket[let] form that can bind multiple variables at once.}
+
+@item{Back-referencing @racket[let*] form that can bind multiple variables at once.}
+
+]
+
+@subsection[#:tag-prefix "a5-" #:style 'unnumbered]{From Dupe++ to Fraud+}
+
+Implement the @racket[abs], unary @racket[-], and @racket[not] operations and
+the @racket[cond] and @racket[case] forms from
+@seclink["Assignment 4"]{Assignment 4} by modifying @tt{interp.rkt},
+@tt{interp-prim.rkt}, @tt{compile.rkt}, and @tt{compile-op.rkt}. You can
+start from your previous code, but you will need to update it to work for the
+code you are given. What's essentially left for you to do is to make sure to
+correctly signal an error (@racket['err]) when these constructs are
+applied to the wrong type of argument.
+
+While you're at it, implement the predicates @racket[integer?] and
+@racket[boolean?] for checking the type of an argument, modeled by the
+@racket[char?] predicate that was covered in the lectures.
+
+@subsection[#:tag-prefix "a5-" #:style 'unnumbered]{Generalizing Let}
+
+The Fraud language has a @tt{let} form that binds a single variable in the
+scope of some expression. This is a restriction of the more general form of
+@racket[let] that binds any number of expressions. So, for example,
+
+@racketblock[
+(let ((x 1) (y 2) (z 3))
+  _e)
+]
+
+simultaneously binds @racket[x], @racket[y], and @racket[z] in the scope of
+@racket[_e].
+
+The syntax of a @racket[let] expression allows any number of binders to occur,
+so @racket[(let () _e)] is valid syntax and is equivalent to @racket[_e].
+
+The binding of each variable is only in-scope within the body, @bold{not} in
+the right-hand sides of any of the @racket[let]. So, for example,
+@racketblock[(let ((x 1) (y x)) 0)] is a syntax error because the occurrence of
+@racket[x] is not bound.
+
+
+@subsection[#:tag-prefix "a5-" #:style 'unnumbered]{Back-Referencing Let}
+
+Similar to @racket[let], there is also @racket[let*] that can also bind any
+number of expressions. The difference is that previous bindings are available
+in the right-hand sides of subsequent bindings. For example,
+
+@racketblock[
+(let* ((x 1) (y 2) (z (add1 y)))
+  _e)
+]
+
+binds @racket[x] to 1, @racket[y] to 2, and @racket[z] to 3 in
+the scope of @racket[_e].
+
+The syntax of a @racket[let*] expression allows any number of binders to occur,
+so @racket[(let* () _e)] is valid syntax and is equivalent to @racket[_e].
+
+Unlike @racket[let], @racketblock[(let* ((x 1) (y x)) 0)] is @emph{not} a
+syntax error. However, bindings are only available forward, so
+@racketblock[(let* ((x y) (y 1)) 0)] @emph{is} a syntax error.
+
+
+
 
 @;{
 The goal of this assignment is to extend the language developed in
@@ -20,7 +114,7 @@ The Extort+ language extends Extort in the follow ways:
 @itemlist[
 @item{adding @racket[when],}
 @item{adding @racket[unless], and}
-@item{bringing forward all the features of Dupe+.}
+@item{bringing forward all the features of Dupe++.}
 ]
 
 

www/assignments/6.scrbl

@@ -1,6 +1,6 @@
 #lang scribble/manual
 @(require "../defns.rkt")
-@title[#:tag "Assignment 6" #:style 'unnumbered]{Assignment 6: Binding many variables}
+@title[#:tag "Assignment 6" #:style 'unnumbered]{Assignment 6: List primitives and n-ary primitives}
 
 @(require (for-label a86 (except-in racket ...)))
 

www/assignments/8.scrbl

@@ -1,6 +1,6 @@
 #lang scribble/manual
 @(require "../defns.rkt")
-@title[#:tag "Assignment 8" #:style 'unnumbered]{Assignment 8: List primitives}
+@title[#:tag "Assignment 8" #:style 'unnumbered]{Assignment 8: Functions with default arguments}
 
 @(require (for-label a86 (except-in racket ...)))
 

www/assignments/9.scrbl

@@ -1,6 +1,6 @@
 #lang scribble/manual
 @(require "../defns.rkt")
-@title[#:tag "Assignment 9" #:style 'unnumbered]{Assignment 9: Functions with default arguments}
+@title[#:tag "Assignment 9" #:style 'unnumbered]{Assignment 9: Patterns}
 
 @(require (for-label a86 (except-in racket ...)))
 

www/defns.rkt

@@ -58,7 +58,6 @@
               "Thursday, September 18, 11:59PM"
               "Thursday, September 25, 11:59PM"
               "Thursday, October 2, 11:59PM"
-              "Thursday, October 9, 11:59PM"
               "Thursday, October 23, 11:59PM"
               "Thursday, October 30, 11:59PM"
               "Thursday, November 6, 11:59PM"