Introduction to Scheme

1
Introduction to Scheme

• Originally developed in 1975 (Steele Sussman)
• Syntactical similar to LISP
• Semantically similar to ALGOL
• Later influenced Common Lisp
• See http//www.informatik.uni-bremen.de/net/hist
  ory.html

2
Scheme Syntax

• Everything is an expression (returns a value)
• Function calls are of the form
• (function arg1 arg2 )
• Control expressions are of the form
• (keyword arg1 arg2 )

3
Primitive Data Types

• Numbers
• Integers, rationals, reals, complex
• Booleans
• f, t
• Characters
• Strings
• Symbols

4
Composite Types

• Pairs
• Lists
• Linked list of pairs
• Vectors

5
Variable Binding

• define
• Introduce (or override) new variable-gtvalue
  binding at current lexical level
• let
• Introduce lexical variable binding

6
Literal Expressions

• (quote literal-expression)
• or
• 'literal-expression

7
Conditional expressions

• if
• (if ( (/ n 2) 0) even odd)
• cond
• and, or

8
Functional Expressions

• lambda
• (define inc (lambda (n) ( n 1)))
• or
• (define (inc n) ( n 1)

9
Built-in Functions

• predicates (number? pair? rational? etc.)
• mathematical functions ( - / max min)
• constructors (cons list vector string)
• conversion (string-gtsymbol symbol-gtstring)
• list-processing (null? car cdr append length
  reverse member assoc)
• string-processing
• vector-processing
• See http//www.scheme.com/tspl2d/objects.html