Software development in Standard ML

Here are the nice things we would like to have from an ML compiler:

• It compiles quickly.

• It produces good error messages.

• You can debug your code interactively.

• The compiler generates a binary you can run on the command line.

• The generated binary might even be fast (not so important for us).

But we can’t have nice things: there is no one compiler that does it all. For this reason, I recommend that you install three compilers. (All three are already installed on the department servers.)

• The Moscow ML compiler compiles quickly and generates a binary you can run on the command line. The error messages are so-so. Interactive debugging is possible, but with so many modules, I don’t know how to make it easy.

  One other issue with Moscow ML: its Standard Basis Library is out of date, so some simple functions like List.concatMap are missing.

  If you can install only one compiler, Moscow ML should be it.

• MLton has great error messages and generates fast, native-code binaries. But it takes a long time to compile, and it cannot be used interactively.

  MLton is worth installing just for the error messages. Don’t wait until you’re frustrated by a cryptic error message; install MLton now.

• Standard ML of New Jersey compiles reasonably quickly and incrementally. The error messages are adequate, and interactive debugging is a snap. Generating a binary to run on the command line is possible, but it is much harder than just installing one of the other compilers that will do it for you.

  Install SML/NJ if you need to debug your ML code interactively.

TL;DR: For fast compilation, Moscow ML. For good error messages, MLton. For interactive debugging and exploration, Standard ML of New Jersey.