Introduction to Scheme prepared by Jason Gould

Installation:

http://www.drscheme.org/

Manual for DrScheme:

http://download.plt-scheme.org/doc/drscheme/

Useful link:

http://download.plt-scheme.org/doc/206p1/html/t-y-scheme/t-y-scheme-Z-H-1.html

Comment Statement:

; this is a comment in Scheme

Data Types:

Simple Data Types:

Booleans:

(boolean? #t)

(boolean? “Hello World”)

(not? #f)

(not? #t)

Numbers:

(number? 42)

(complex? 2+3i)

(real? 3.1416)

(rational? 22/7)

(integer? 42)

(eqv? 42 42)

(= 42 42)

(+ 1 2 3)

(expt 2 3)

(max 1 2 3 4)

(min 1 2 3 4)

Characters

(char? #\c)

Symbol

‘xyz

Compound Data Types:

Strings

(string #\h #\e #\l #\l #\o)

(define greeting “Hello , Hello !”)

(string- ref greeting 0) => #\H

Vectors

Dotted Pairs and lists

Conversion between data type:

(char->integer #\d) => 100 look at http://www.asciitable.com/ to see why you get 100 as the answer.

Procedures:

We can create our own procedures by using the lambda keyword

(define add2

(lambda(x) (+ x 2)))

then you can call (add2 4) and you will get 6

(define area

(lambda(length)

(* length)))

then you can call (area 3 4) and you will get 12

Simple If statement:

(define test

(lambda(x) (if(> x 2)'safe 'unsafe)))

Calling other procedures inside a procedure:

(define iseven

(lambda (n)

(if (= n 0) #t

(isodd (- n 1)))))

(define isodd

(lambda (n)

(if (= n 0) #f

(iseven (- n 1)))))

Recursion with Factorials:

(define factorial

(lambda (n)

(if (= n 0) 1

(* n (factorial (- n 1))))))