13:20-15:50 at W831

Assignment

Published date

Oct. 22, 2018

Due date

To be placed on OCW-i

Method of Submission

Upload answer2.ml at the respective page of OCW-i.

Delayed Submission

Each submission is weighed according to half-value period of 10 days. That means if you submit a perfect answer 30 days after the due date, you will receive \(1/8\) the full points. In other words, you lose \(1 - 1/2^{1/10} \approx 6.7\text {%}\) points each day after the due date has passed. It is very wise to keep the due date.¹

Problem

Complete the definition of unparse that takes an AST (abstract syntax tree as defined in syntax.ml) of the Min Caml compiler and generates its source program.

• The AST is ast(\(P\))

• Correctness of unparsing:

  For any Min Caml program \(P\): ast(\(P\)) = ast(unparse(ast(\(P\))))

  In other words, for an AST \(t\) = ast(\(P\)), ast(unparse(\(t\))) = \(t\).

• It is desirable for unparse to generate properly indented programs that look nice to human eyes. An answer that gives a beautifully indented out will get extra bonus points. The amount of bonus is written in the top page.

Obtaining the template file

Download a template answer2.ml and save it where you built min-caml.top. The template contains 25 test cases.

Examining the AST

Run min-caml.top and type in ast <a min-caml expression>, where <a min-caml expression> is the expression that you want to examine.

Testing your unparser

If you are (half-) finished with the assignment, run the code with ocaml answer2.ml

answer2.ml must stay at the directory where you built min-caml.top and you must run the ocaml answer2.ml command at this directory.

Use ocaml. Not min-caml.top. answer2.ml is written in OCaml.

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