PA1: Rosetta 

# What is submitted:
- rosetta.py: program code written in Python
- rosetta.ml: program code writte in Ocaml
- simple.list: a simple input file
- readme.txt: this document

# How to run

tnguyen@cse:~> uname -a
Linux cse 4.12.14-lp151.28.91-default #1 SMP Tue Jan 12 23:05:46 UTC 2021 (e284d31) x86_64 x86_64 x86_64 GNU/Linux
tnguyen@cse:~> cd pa1

tnguyen@cse:~/pa1> cat simple.list
learn C
read the C tutorial
do PA1
learn C


tnguyen@cse:~/pa1> python rosetta.py < simple.list  
read the C tutorial
learn C
do PA1

tnguyen@cse:~/pa1> ocamlc rosetta.ml -o rosetta.exe
tnguyen@cse:~/pa1> ./rosetta.exe <simple.list 
read the C tutorial
learn C
do PA1

# Program Design

For the Python implementation, I read lines from stdin and store contents in a set.  I compute task dependencies and constraints from the set. My program has 2 phases:  the first phase compute dependencies and outputs `cycle` if it exists and exit. Thus, the second phase only proceeds to print the results only if the first phase does not find any cycle.

The Ocaml implementation is similar to the Python, except that instead of using set I use hashtable (which seems quite easy to use in Ocaml, comparing to set).

# Evaluation
I have tested my implementation on the given tests. Unfortunately, my program only works for 8/10 tests. It fails test-X and test-Y. (if you know the reason, put them here)

# Addition Questions/Comments
1. What are some challenging parts for this assignment? What did you do to solve them?
It was a bit difficult to do OCAML because this is my first experience in using a functional language. 
2. Suggestions for both the instructor and future students for this assignment?
Instructor: tell the student to start early as lots of debugging are involved
Students: Ocaml type inference is really useful.  But if you are not used to it, consider explicitly put the type directly when you declare variables, e.g.,  let x:int = 3 in ...  instead of just let x = 3 in ...