signature MLTON_INT_INF =
   sig
      type t = IntInf.int

      val areSmall: t * t -> bool
      val gcd: t * t -> t
      val isSmall: t -> bool

      structure BigWord : WORD
      structure SmallInt : INTEGER
      datatype rep =
         Big of BigWord.word vector
       | Small of SmallInt.int
      val rep: t -> rep
   end

MLton represents an arbitrary precision integer either as an unboxed word with the bottom bit set to 1 and the top bits representing a small signed integer, or as a pointer to a vector of words, where the first word indicates the sign and the rest are the limbs of a GnuMP big integer.

• type t
  the same as type IntInf.int.

• areSmall (a, b)
  returns true iff both a and b are small.

• gcd (a, b)
  uses the GnuMP's fast gcd implementation.

• isSmall a
  returns true iff a is small.

• BigWord : WORD
  representation of a big IntInf.int as a vector of words; on 32-bit platforms, BigWord is likely to be equivalent to Word32, and on 64-bit platforms, BigWord is likely to be equivalent to Word64.

• SmallInt : INTEGER
  representation of a small IntInf.int as a signed integer; on 32-bit platforms, SmallInt is likely to be equivalent to Int32, and on 64-bit platforms, SmallInt is likely to be equivalent to Int64.

• datatype rep
  the underlying representation of an IntInf.int.

• rep i
  returns the underlying representation of i.