ML-NLFFI is the no-longer-foreign-function interface library for SML.
As of 20050212, MLton has an initial port of ML-NLFFI from SML/NJ to MLton. All of the ML-NLFFI functionality is present.
Additionally, MLton has an initial port of the mlnlffigen tool from SML/NJ to MLton. Due to low-level details, the code generated by SML/NJ’s ml-nlffigen is not compatible with MLton, and vice-versa. However, the generated code has the same interface, so portable client code can be written. MLton’s mlnlffigen does not currently support C functions with struct or union arguments.
You can import the ML-NLFFI Library into an MLB file with
MLB file Description
# MLNLFFI Library $c $(SML_LIB)/mlnlffi-lib $c/c.cm $(SML_LIB)/mlnlffi-lib/mlnlffi-lib.mlb
This will automatically convert a $/c.cm import in an input .cm file into a $(SML_LIB)/mlnlffi-lib/mlnlffi-lib.mlb import in the output .mlb file.