Assignment#2

This assignment has two components. Interpreter and Type inference.
(A) Interpretation

(A1, 10 marks) Write an interpreter for minischeme. You may use the rules discussed in the class (many of them can be used verbatim). A sample interpreter for a subset of the same can be found here, that can interpret the syntax tree given in tree.scm. You will need two other helper files: records.scm and recscm.scm.

To submit:
Filename: interpreter-regular.scm
Expected output: the value returned by the scheme program.

(A2, 40 marks) Write an interpreter for minischeme, assuming call-by name semantics.

To submit:
Filename: interpreter-lazy.scm
Expected output: the value returned by the scheme program, if evaluated in lazy manner.

(B) Type Inference (50 marks):
Write a program to infer the type of the scheme expression. Assume the following rules:
- valid types are generated from the following grammar
t : Bool | Int | t -> t
- Standard rules of type consistency apply to all the expressions.

To submit:
Filename: type-infer.scm
Expected output: a valid type or "Type Error"

Example, if the scheme expression is

 (lambda (x) (+ 3 x)) 

 (lambda (x) (+ 3 x) 6) 

 (lambda (x) (+ 3 x) #t) 

Follow the example invocation:

echo "(if #t (+ 3 4) (lambda (x) (+ 6 x) 3))" | java -jar sst.jar  > tree.scm

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Submission guidelines:

Your submissions should be a single .tar.gz file of the form .tar.gz.
Unzipping it must produce a single directory matching your roll number e.g., CS20B001.
This directory must have a single subdirectory: A2 and file checklist.txt [see moodle for the details on Checklist.txt]
All the .scm files for the given questions must be present in this directory.

The following sample commands should be able to run the respective submissions:

tar xvzf .tar.gz
cd yourroll/A2
for x in *scm
do
	q=$(basename $x .scm) # Get the question no. A1, A2 or B
	for t in /tmp/$q/*scm # say, the test input for that question is stored in a file in the /tmp directory.
        do
		cat $t | java -jar sst.jar > tree.scm
		mzscheme <  $x
done