Table of ContentsThe Haskell Programming Language An imperative language Scheme is still imperative A more realistic example Factoring out an expression Haskell: Works with fewer ifs and buts Overview of Haskell Haskell’s History The brevity of Haskell Quicksort in two lines! Haskell syntax Syntax: Haskell vs. Scheme Hugs98 Haskell Users Gofer System One gotcha of Hugs98 Learning Haskell Some simple expressions When things do not go according to plan... More errors... A simple example Fibonnaci numbers Mathematical notation Fibonnaci numbers in Haskell Two different approaches Indentation matters! Implicit vs. explicit grouping Explicit grouping is useful at the repl Function application Functions with multiple arguments Currying Partial application Specializations Lambda expression syntax Functions vs. operators Other operators Why use tuples for arguments? Ackermann function (Wilhelm Ackermann, 1928) Patterns Wildcards in patterns Patterns and case expressions Conditionals List shorthands List comprehension Compare to using higher order functions Comprehension instead of nested loops Values have types Functions have types too Built in types Dynamic vs. Static typing Advantages of static typing Static typing rules Application rule Cancellation rule Function rule List rule Tuple rule Length of list of integers Applying len to [Char] What does len rely on? Type variables Polymorphic functions Type inference Type unification Unification is the intersection of the described types Evaluation in Haskell Not all arguments get evaluated Eager evaluation vs. lazy evaluation Lazy evaluation is efficient No need for special forms Outside-in evaluation avoids intermediate lists |
Author: Greg J. Badros
Email: badros@cs.washington.edu Home Page: http://www.cs.washington.edu/education/courses/341/CurrentQtr |