Chapter 10 - Teach Yourself Scheme in Fixnum Days[Go to...

Info icon This preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Teach Yourself Scheme in Fixnum Days [Go to first , previous , next page; contents ; index ] Chapter 10 Alists and tables An association list , or alist , is a Scheme list of a special format. Each element of the list is a cons cell, the car of which is called a key , the cdr being the value associated with the key. Eg, ((a . 1) (b . 2) (c . 3)) The procedure call (assv k al) finds the cons cell associated with key k in alist al . The keys of the alist are compared against the given k using the equality predicate eqv? . In general, though we may want a different predicate for key comparison. For instance, if the keys were case-insensitive strings, the predicate eqv? is not very useful. We now define a structure called table , which is a souped-up alist that allows user-defined predicates on its keys. Its fields are equ and alist . (defstruct table (equ eqv?) (alist '())) (The default predicate is eqv? -- as for an ordinary alist -- and the alist is initially empty.) We will use the procedure table-get
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern