03-transformers: Transformers and Testing (240 points)

Overview

The overall objective of this assignment is to get some experience using Monad-Transformers and Property-based Testing.

The assignment is in the following files that you will modify

• BST.hs
• Eval.hs

The following file contains useful definitions but does not need to be modified:

• Types.hs

Finally, there are aTest.hs has some sample tests to be used
to check your assignments before submitting.

• test/Test.hs

You should only modify the parts of the files which say:

error "fill this in"

with suitable Haskell implementations.

You are free to write and use any helper functions.

Instructions

Assignment Testing and Evaluation

Most of the points, will be awarded automatically, by evaluating your functions against a given test suite.

Tests.hs contains a very small suite of tests which gives you a flavor of of these tests. When you run

$ make test

Your last lines should have

All N tests passed (...)
OVERALL SCORE = ... / ...

or

K out of N tests failed
OVERALL SCORE = ... / ...

If your output does not have one of the above your code will receive a zero

If for some problem, you cannot get the code to compile, leave it as is with the error "fill me in" with your partial solution enclosed below as a comment.

The other lines will give you a readout for each test. You are encouraged to try to understand the testing code, but you will not be graded on this.

Your code must typecheck against the given type signatures. Feel free to add your own tests to this file to exercise the functions you write. As before, you can compile the code by doing stack build and load in ghci by doing stack ghci.

Learn to read the documentation

Submission Instructions

To submit your code, just do:

$ make turnin

Collaborators

As before please add the name of any collaborator in the file COLLABORATORS.md

Problem 1: Binary Search Trees

Fill in the missing code in BST.hs

Problem 2: An Evaluator for WHILE++

Read but do not modify the type and other definitions in Types.hs

Fill in the missing code in Eval.hs