1 / 12

Racket Last Structs, Lambda, Module

Racket Last Structs, Lambda, Module. CSC270 Pepper. major portions credited to http://learnxinyminutes.com/docs/racket/. Structs. ; Define structure: (struct student (name gpa age)) ; structure type definition: (define s1 (student "amy jones" 3.0 20))

kathyweaver
Download Presentation

Racket Last Structs, Lambda, Module

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Racket Last Structs, Lambda, Module CSC270 Pepper major portions credited to http://learnxinyminutes.com/docs/racket/

  2. Structs ; Define structure: (struct student (name gpa age)) ; structure type definition: (define s1 (student "amy jones" 3.0 20)) ; use of one part of struct variable: (student-name s1) ; check type : (student? s1 )

  3. Shape Structures • (struct circle (radius)) • (define c1 (circle 10)) • (define c2 (circle 12)) • (structrect (length width)) • (define r1 (rect 10 20)) • (define r2 (rect 11 12))

  4. Area Functions (define (area a-shape) (cond [(rect? a-shape) (* (rect-length a-shape) (rect-width a-shape))] [ (circle? a-shape) (* (expt (circle-radius a-shape) 2)pi)])) (area c1) (area r1) (area (rect 10 30)

  5. Functions Passing in Functions • First class functions (define (square num) (* numnum)) (define (pow3 num) (* numnumnum)) (define (calcnumberfunc) (numberfunc 10)) (calc square); (calc pow3); Plus Remember map: • (define (add3 x) (+ x 3)) • (map add3 '(1 2 3))

  6. Lambda Functions (lambda () "Hello") ; surround with parentheses to call (( lambda () "Hello")) ; function with a parm (lambda (num) (+ num 3)) ; surround with parentheses to call ((lambda (num) (+ num 3)) 5) All functions have an implied lambda

  7. Define and Lambda ; assign a lambda function to a symbol (define Lhello-world ( lambda() "Hello")) ; same as (define (Lhello-world) "hello") (Lhello-world) (define Ladd3 ( lambda (num) (+ num 3))) ; second same as (define (Ladd3 num) (+ num 3)) (Ladd3 5) ; see how all functions have an implied lambda?

  8. Functions Passing in Functions (define (triangleperm a b c) (+ a b c)) (define (equiTriangle a) (triangleperm a a a)); (calc equiTriangle); Or instead of defining equiTriangle, create an anonymous function: (calc (lambda (x) (triangleperm x x x)))

  9. Map Lambda functions • Define a function Use it in map • (define (add3 x) (+ x 3)) • (map add3 '(1 2 3)) • Define that same function anonymously • (map (lambda (i) (+ i 3)) '(1 2 3))

  10. Adding New Commands EASY (define-syntax-rule (swap! x y) (let ([temp x]) (set! x y) (set! y temp))) (define x 3) (define y 4) (swap! x y) x y

  11. Modules • create it with (module moduleName itsBase) example (module cake racket/base) • list functions the importer can use with (provide functionName) example (provide bake-cake) • no indication of parameters needed • To import a module : (require ModuleName) example (require picturing-programs)

  12. Important Concepts • Define data in parts : structure • Functions can take in functions as parms • On the fly functions give flexibility

More Related