SM2-TES: Functional Programming and Property-Based Testing

This repository is a placeholder for example code from the course 'SM2-TES: Functional Programming and Property-Based Testing' held at the University of Southern Denmark, Spring 2020.

Useful resources

OCaml standard library

QCheck documentation

Top-level directives:

Both utop and the ocaml read-eval-print loop accepts a number of "directives" documented in the manual, chapter 10.2.

These are strictly speaking not part of the OCaml language - just helpful instructions to the interactive interpreters. As such, I wouldn't put them in source code.

• #use "filename.ml";; loads OCaml source code into the read-eval-print loop. It stops on the first error.

• #show identifier;; prints the type of a variable or module.

• #use "topfind";; loads a helper program to easily load packages. topfind is loaded automatically by utop.

  After loading topfind additional directives are available:

  • #require "packagename";; for loading a package, e.g., qcheck.

  • #list;; prints a list of installed packages

• ...

Installation instructions:

You need to install

• OCaml and the qcheck library (use OCaml's package manager OPAM for this)
• an editor (VS Code) to program/edit OCaml code.

The below instructions are adapted from Scott F. Smith's instructions.

For Linux and Mac:

0. Install dependencies (m4, make, gcc):

    sudo apt-get install m4 make gcc
   

   (on Ubuntu/Debian Linux and Linux Subsystem)

   On Mac: install the three dependencies via macports or homebrew.

1. Install opam. See the OPAM install page for instructions. Depending on which method you use you may then need to run some terminal commands, e.g., for Ubuntu (and Ubuntu under Windows Subsystem for Linux):

    sudo add-apt-repository ppa:avsm/ppa
    sudo apt update
    sudo apt install opam
   

2. opam init to initialize OPAM;

   opam init --disable-sandboxing (on Windows)

   Answer y to allowing opam to add changes to your .profile.

3. opam switch create 4.10.0 to build OCaml version 4.10.0;

   If step 2 above finishes with installed ocaml.4.10.0 you can skip this step.

4. eval $(opam env) to let the shell know where the OPAM files are.

5. Once you have the basics installed, run the following command to install additional necessary packages for the class:

    opam install qcheck ocamlfind ocamlbuild merlin ocp-indent user-setup utop
   

For Windows:

On Windows 10: Install MSFT Bash on Windows which once you have set up will allow you to follow the Linux Ubuntu install instructions to get opam. (Windows 10 only for this unfortunately and it may have some incompatibilities).

For older Windows versions:

• Install a virtual machine with Linux as explained here and install OCaml on that or
• Try this installer: https://fdopen.github.io/opam-repository-mingw/installation/
• Last resort: call Jan

Checking your OCaml and QCheck installation:

To ensure that OCaml and QCheck is properly installed:

1. check that you can use the arrow keys and backspace in the OCaml toplevel if you run the command utop

2. check that in the utop toplevel

  #list;;

lists package qcheck (version: 0.5 or above)

For the ocaml toplevel you need to write two lines:

  #use "topfind";;
  #list;;

3. check that you can run QCheck from the toplevel following this screencast and from utop with this screencast

4. check that you can build a QCheck test with ocamlbuild following this screencast

   the code for the latter is also available here: https://github.com/jmid/qcheck-example

Installing VS Code:

• Install VS Code https://code.visualstudio.com/

• Install the 'OCaml and Reason IDE' extension to get syntax highlighting, type information, etc: from the 'View' menu select 'Extensions, then type in OCaml and this extension will show up; install it. You can also easily run an ocaml shell from within VSCode, just open it up from the 'Terminal' menu and type ocaml or utop into the terminal.

• On Windows 10: install the 'remote WSL' extension as described here:

  https://code.visualstudio.com/docs/remote/wsl

  This way, VS Code can find ocamlfind and ocamlmerlin in the Windows Subsystem for Linux without further configuration.

  Enabling a bash Terminal rather than a 'Powershell' will also let you run ocaml or utop from within VS Code.

Troubleshooting: If VS Code complains that it cannot find the QCheck module on either Windows, Mac, or Linux, create a file called .merlin with the content

PKG qcheck

This way, you inform the language server merlin of the qcheck dependency.