CSE 230 HW

Download

1. Use the fork link from the class website to create your private clone of the starter code.

2. Do git clone https://github.com/ucsd-cse230-wi19/hw3-XXX where XXX is your private repo.

Link to Upstream

3. Link your clone to the "upstream" to get any updates

$ make upstream

after this you can get "updates" (in case we modify the starter code), with

$ make update

Do the Assignment

4. Edit the files and run LH

$ make 

repeat this until LH says "SAFE"

Submit

5. Save (and submit) your work with:

$ git commit -a -m MESSAGE
$ git push

Hint on Q2

To implement full_asimp note that NAExp expressions look like:

Plus (Var x1) (Plus (Var x2) ... (Plus (Var xn) (N c)))

and the key is to write a function

plus_naexp :: NAExp -> NAExp -> NAExp 

which, when given two NAExps of the form

a1 = Plus (Var x1) (Plus (Var x2) ... (Plus (Var xn) (N c)))

a2 = Plus (Var y1) (Plus (Var y2) ... (Plus (Var ym) (N d)))

should essentially recursively go down the first expression till it hits the rightmost constant N c and replace it with a2-where-d-is-replaced with c+d.

To do the last step, you should write a function

cplus :: Int -> NAExp -> NAExp 

such that cplus n a recurses on a until it finds its rightmost constant c which is then replaced with n+c.

You should then use cplus to implement plus_naexp a1 a2 by recursively going inside a1 till you find its rightmost constant c which should then be replaced by cplus c a2.