MLtonIntInf

MLton 20241230

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
      val fromRep : rep -> t option
   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 GMP 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 GMP’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.
fromRep r

converts from the underlying representation back to an IntInf.int. If fromRep r is given anything besides the valid result of rep i for some i, this function call will return NONE.