Answered: Consider the function second xs = head…

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

See similar textbooks

Related questions

Concept explainers

Question

Consider the function

second xs = head (tail xs)

What is its type?

Explain why "second" has the type that it has, i.e., "tail :: [a] ->
[a]", hence "xs :: [a]", and "head :: [a] -> a", etc. Why does
chaining them together like in the definition of "second" give us the
type that it has?

Note: this will use the fact that if "f" is a function that maps
arguments of type "a" to results of type "b", and "e" is an expression
of type "a", then the application "f e" has type "b", that is:

if "f :: a -> b" and "e :: a" then "f e :: b"

Consider the function

swap (x,y) = (y,x)

What is its type?

Why can "x" and "y" correspond to
different types in general?

Expert Solution

Trending now

This is a popular solution!

Step by step

Solved in 2 steps

SEE SOLUTION Check out a sample Q&A here

Knowledge Booster

Learn more about

Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, computer-science and related others by exploring similar questions and additional content below.

Similar questions