Introduction

In class we looked at depython, some types for representing python abstract syntax trees.

In python you can introspect code using the ast module.

import ast

ast.dump(ast.parse("123"))

The result is

Module(body=[Expr(value=Num(n=123))])

A more complicated example:

ast.dump(ast.parse("2 + 3"))

Results in

Module(body=[Expr(value=BinOp(left=Num(n=2), op=Add(), right=Num(n=3)))])

Types

We can define OCaml types similar to the above representations of python ast

type binop = Add | Sub | Mult | Div

type exp =
    | Num of int
    | BinOp of exp * binop * exp

type stm =
    | Expr of exp

type prog =
    | Module of stm list

I have made a github repository with the data types, some build instructions, and the beginning of a test suite.

Homework

Implement an interpreter for the prog type, following the skeleton in the example code. See the README.md file for more details. Be careful to not change the types of the funcion or data. My test suite should build against your dedepython file.

dedepython - OCaml types for a subset of python

Introduction

Types

Homework