[SOLVED] Haskell file system Assignment 1 CIS 252 Intro to Computer Science

Assignment 1 CIS 252 Intro to Computer Science

Coverage & Logistics
This homework covers material through the first three chapters (with an empha-
sis on Chapters 1-2) of Haskell: The Craft of Functional Programming (HCFP),
as well as some Unix basics.

This homework is officially due in class on Thursday, January 26. However, it
comes with an automatic extension: anything submitted to the CIS 252 bin near
CST 4-226 by noon on Friday, January 27 will be accepted as being on time.

You should work solo on this assignment.

Part 1: Unix Exercises
Consider the following (partial) file system hierarchy:

1

/

2

courses/

3

Users/

4

cmc/

5

runes/

6

potions/

7

staff/

8

student/

9

hagrid/

11

apwbd/

13

hpotter/

14

hjg/

15

rbw/

10

courses/

12

projects/

16

courses/

17

projects/

18

spells/

Here are a couple comments regarding how to read this diagram:

Each node represents a Unix directory, which may contain additional files
that are not included in the diagram.

Each node contains a numeric label at the top, in addition to the direc-
torys name: for example, the root node (/) has the numeric label 1.
These numeric labels are intended merely as identification for the questions
that follow, since (for example) there are three different directories with the
name courses.

Suppose that Hermiones home directory is directory #14 and that her cur-
rent working directory is directory #5.

1. What is the absolute pathname for Hermiones home directory?

2. If Hermione executed the Unix command pwd, what would the systems
response be?

3. If Hermione executed the Unix command cd .. and then executed the
command pwd, what would the systems response be?

4. If Hermione executed the Unix command cd ~/courses and then executed
the command pwd, what would the systems response be?

5. For each of the following tasks, give the Unix command (or series of com-
mands) that Hermione would need to complete the task; in many cases,
there will be more than one correct answer. You should assume that each
task is completed independently of the others (i.e., changes made in one
task do not affect other tasks), that her home directory is directory #14,
and that her current working directory is directory #5.

As an example, Ive completed the first one (?) for you.

? Get a long listing (i.e., includes file permissions and creation dates) of
directory #4

Sample answer: ls -l ../cmc

(a) Make a subdirectory called new in directory #14

(b) Move the file results.pdf from directory #18 to directory #16

(c) Copy the file polyjuice from directory #6 to directory #17, but give
it the name mission

(d) Change her working directory to directory #12

(e) List all files (including those that begin with a period) in her home
directory

(f) Create a subdirectory in directory #16 called hws and then place a
copy of the file hw2.hs (located in directory #5) into that new subdi-
rectory

Spring 2017

Assignment 1 CIS 252 Intro to Computer Science

Part 2: Haskell Exercises
Please note: The solution for each problems should be written in a single
line (two lines, if you count the type declaration) of Haskell.

General advice: Work on one problem at a time: get it working before moving
on to the next problem. (Writing all your code at once will likely result in a
series of errors and a lot of frustration on your part. It is usually much easier
to work in small increments.)

6. Write a one-line Haskell function

between :: Int -> Int -> Int -> Bool

such that between m y z returns True exactly when m is (strictly) between
y and z (i.e., y is less than m and m is less than z); the function should
return False in all other cases.

For example, between 10 3 15 should return True, but between 3 7 6,
between 8 5 7, and between 10 10 15 should all return False.

7. The exclusive or of two boolean values is calculated as follows:

When exactly one of the two values is True, their exclusive-or is True.
When both values are True (or both are False), their exclusive-or is
False.

Write a one-line Haskell function

xor :: Bool -> Bool -> Bool

such that xor e1 e2 calculates the exclusive-or of e1 and e2.

For example, xor True False and xor False True should both return
True, where xor True True and xor False False should return False.

8. Youre probably familiar with the Fahrenheit and Celsius temperature
scales, but they are not the only temperature scales to ever be used. The
Delisle temperature scale was invented by Joseph-Nicolas Delisle in 1738.

The relationship between a Fahrenheit temperature f and the correspond-
ing Delisle temperature d is given as follows:

f = 212.0
6

5
d

For example, 10 Delisle is 200 Fahrenheit; 5 Delisle is 218 Fahrenheit.
(Yes, in the Delisle scale, warmer temperatures have smaller numbers
associated with them.)

(a) Write a one-line Haskell function

convertDtoF :: Float -> Float

such that convertDtoF temp returns the Fahrenheit equivalent of
the Delisle temperature temp. For example, convertDtoF 10 returns
200.0.

(b) Write a one-line Haskell function

convertFtoD :: Float -> Float

such that convertFtoD temp returns the Delisle equivalent of the
Fahrenheit temperature temp. For example, convertFtoD 200 returns
10.0.

What to turn in

You will need to submit the following (please staple your pages!):

The disclosure cover sheet

Part I: Unix questions Turn in written (or typed) answers to the Unix
questions.

Part II: Haskell exercises Turn in hard copies of (1) your source code and
(2) a transcript demonstrating convincingly that your code is correct.

To generate the transcript:

Include all of the tests that appear in the hw1tests file. (You may
include additional tests if youd like, but these tests are necessary.)

Generate your final transcript only after you have gotten all of
your code to work. Take pity on the graders, and make sure that
your solutions will be easy to grade/verify. (If they have to work too
hard to find your answers, you will lose points.)

Spring 2017

http://www.cis.syr.edu/~sueo/cis252/coursework/hw1tests