MLton 20210117

# FAQ

Feel free to ask questions and to update answers by editing this page. Since we try to make as much information as possible available on the web site and we like to avoid duplication, many of the answers are simply links to a web page that answers the question.

## How do you pronounce MLton?

Pronounce

## What SML software has been ported to MLton?

Libraries

## What graphical libraries are available for MLton?

Libraries

## How does MLton’s performance compare to other SML compilers and to other languages?

MLton has excellent performance.

## Does MLton treat monomorphic arrays and vectors specially?

MLton implements monomorphic arrays and vectors (e.g. BoolArray, Word8Vector) exactly as instantiations of their polymorphic counterpart (e.g. bool array, Word8.word vector). Thus, there is no need to use the monomorphic versions except when required to interface with the Basis Library or for portability with other SML implementations.

## Why do I get a Segfault/Bus error in a program that uses IntInf/LargeInt to calculate numbers with several hundred thousand digits?

GMP

## How can I decrease compile-time memory usage?

- Compile with -verbose 3 to find out if the problem is due to an SSA optimization pass. If so, compile with -disable-pass pass to skip that pass.

- Compile with @MLton hash-cons 0.5 --, which will instruct the runtime to hash cons the heap every other GC.

- Compile with -polyvariance false, which is an undocumented option that causes less code duplication.

Also, please Contact us to let us know the problem to help us better understand MLton’s limitations.

## How portable is SML code across SML compilers?

StandardMLPortability