Nativeint(3)

💅 Nativeint(3) — the OCaml library glow-up

okay so bestie, welcome to Nativeint, straight out of the OCaml library (that's the manual, section 3, iykyk). This is the page for processor-native integers, and honestly? It's giving exactly what it says on the tin. 🎀

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🌸 NAME

Nativeint — Processor-native integers. ✨

Like, that's the whole vibe: integers that are native to your processor. No cap, that's the name and that's the job. 🦋

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🧚 Module

Module Nativeint 👑

(yeah, the module is literally called Nativeint — main character energy, we love a self-titled moment 💅)

Processor-native integers. 💅 This module is literally all about the type nativeint, which is signed 32-bit integers on 32-bit platforms and signed 64-bit integers on 64-bit platforms. This integer type has exactly the same width as that of a pointer type in the C compiler. All arithmetic operations over nativeint are taken modulo 2^32 or 2^64 depending on the word size of the architecture. No cap.

⚠️ Performance notice, bestie: values of type nativeint occupy more memory space than values of type int, and arithmetic operations on nativeint are generally slower than those on int. Use nativeint only when the application requires the extra bit of precision over the int type. It’s giving “special occasion only” energy.

Literals for native integers are suffixed by n:

let zero: nativeint = 0n
let one: nativeint = 1n
let m_one: nativeint = -1n

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val zero : nativeint

The native integer 0. The icon. The beginning. 🎀

val one : nativeint

The native integer 1. Main character energy fr fr.

val minus_one : nativeint

The native integer -1. Yes, it’s that girl. 💅

val neg : nativeint -> nativeint

Unary negation. Flip the sign, slay.

val add : nativeint -> nativeint -> nativeint

Addition. Math but make it native.

val sub : nativeint -> nativeint -> nativeint

Subtraction. Taking things away, respectfully.

val mul : nativeint -> nativeint -> nativeint

Multiplication. Times tables but processor-native.

val div : nativeint -> nativeint -> nativeint

Integer division. This division rounds the real quotient of its arguments towards zero, as specified for (/).

Raises Division_by_zero if the second argument is zero. 🚨

val unsigned_div : nativeint -> nativeint -> nativeint

Same as Nativeint.div, except that arguments and result are interpreted as unsigned native integers.

Since 4.08

val rem : nativeint -> nativeint -> nativeint

Integer remainder. If y is not zero, the result of Nativeint.rem x y satisfies the following properties: Nativeint.zero <= Nativeint.rem x y < Nativeint.abs y and x = Nativeint.add (Nativeint.mul (Nativeint.div x y) y) (Nativeint.rem x y). If y = 0, Nativeint.rem x y raises Division_by_zero.

val unsigned_rem : nativeint -> nativeint -> nativeint

Same as Nativeint.rem, except that arguments and result are interpreted as unsigned native integers.

Since 4.08

val fdiv : nativeint -> nativeint -> nativeint

Floor division. fdiv x y is the real quotient x / y rounded down to an integer. We have fdiv x y <= div x y <= cdiv x y and cdiv x y - fdiv x y <= 1.

Since 5.5

Raises Division_by_zero if the second argument is 0.

val cdiv : nativeint -> nativeint -> nativeint

Ceil division. cdiv x y is the real quotient x / y rounded up to an integer. We have fdiv x y <= div x y <= cdiv x y and cdiv x y - fdiv x y <= 1.

Since 5.5

Raises Division_by_zero if the second argument is 0.

val ediv : nativeint -> nativeint -> nativeint

Euclidean division. ediv x y is the real quotient x / y rounded down to an integer if y > 0 and rounded up to an integer if y < 0. The remainder erem x y = x - ediv x y * y is always non-negative. Moreover, ediv x (-y) = - ediv x y.

Since 5.5

Raises Division_by_zero if the second argument is 0.

val erem : nativeint -> nativeint -> nativeint

Euclidean remainder. If y is not zero, we have x = ediv x y * y + erem x y and 0 <= erem x y <= abs y - 1. The result of erem x y is always non-negative, unlike the result of rem x y, which has the sign of x. That’s the whole point, periodt.

Since 5.5

Raises Division_by_zero if the second argument is 0.

val succ : nativeint -> nativeint

Successor. Nativeint.succ x is Nativeint.add x Nativeint.one. Basically “plus one, bestie.”

val pred : nativeint -> nativeint

Predecessor. Nativeint.pred x is Nativeint.sub x Nativeint.one. Basically “minus one, bestie.”

val abs : nativeint -> nativeint

abs x is the absolute value of x. On min_int this is min_int itself and thus remains negative. Yes, that’s cursed, but it’s canon. 😭

val size : int

The size in bits of a native integer. This is equal to 32 on a 32-bit platform and to 64 on a 64-bit platform.

val max_int : nativeint

The greatest representable native integer, either 2^31 - 1 on a 32-bit platform, or 2^63 - 1 on a 64-bit platform.

val min_int : nativeint

The smallest representable native integer, either -2^31 on a 32-bit platform, or -2^63 on a 64-bit platform.

val logand : nativeint -> nativeint -> nativeint

Bitwise logical and.

val logor : nativeint -> nativeint -> nativeint

Bitwise logical or.

val logxor : nativeint -> nativeint -> nativeint

Bitwise logical exclusive or.

val lognot : nativeint -> nativeint

Bitwise logical negation.

val shift_left : nativeint -> int -> nativeint

Nativeint.shift_left x y shifts x to the left by y bits. The result is unspecified if y < 0 or y >= bitsize, where bitsize is 32 on a 32-bit platform and 64 on a 64-bit platform.

🫶 Unspecified means don’t come crying to me if it does something weird. Stick to the valid range.

val shift_right : nativeint -> int -> nativeint

Nativeint.shift_right x y shifts x to the right by y bits. This is an arithmetic shift: the sign bit of x is replicated and inserted in the vacated bits. The result is unspecified if y < 0 or y >= bitsize.

val shift_right_logical : nativeint -> int -> nativeint

Nativeint.shift_right_logical x y shifts x to the right by y bits. This is a logical shift: zeroes are inserted in the vacated bits regardless of the sign of x. The result is unspecified if y < 0 or y >= bitsize.

val of_int : int -> nativeint

Convert the given integer (type int) to a native integer (type nativeint).

val to_int : nativeint -> int

Convert the given native integer (type nativeint) to an integer (type int). The high-order bit is lost during the conversion. She’s leaking bits, your honor. 💀

val unsigned_to_int : nativeint -> int option

Same as Nativeint.to_int, but interprets the argument as an unsigned integer. Returns None if the unsigned value of the argument cannot fit into an int.

Since 4.08

val of_float : float -> nativeint

Convert the given floating-point number to a native integer, discarding the fractional part (truncate towards 0). If the truncated floating-point number is outside the range [Nativeint.min_int, Nativeint.max_int], no exception is raised, and an unspecified, platform-dependent integer is returned.

⚠️ No exception? Out-of-range? Unspecified? That’s not a vibe check I’d trust. Keep it in range, bestie.

val to_float : nativeint -> float

Convert the given native integer to a floating-point number.

val of_int32 : int32 -> nativeint

Convert the given 32-bit integer (type int32) to a native integer.

val to_int32 : nativeint -> int32

Convert the given native integer to a 32-bit integer (type int32). On 64-bit platforms, the 64-bit native integer is taken modulo 2^32, i.e. the top 32 bits are lost. On 32-bit platforms, the conversion is exact. Slay for 32-bit, 😭 for 64-bit.

val of_string : string -> nativeint

Convert the given string to a native integer. The string is read in decimal (by default, or if the string begins with 0u) or in hexadecimal, octal or binary if the string begins with 0x, 0o or 0b respectively.

The 0u prefix reads the input as an unsigned integer in the range [0, 2*Nativeint.max_int+1]. If the input exceeds Nativeint.max_int it is converted to the signed integer Int64.min_int + input - Nativeint.max_int - 1.

Raises Failure if the given string is not a valid representation of an integer, or if the integer represented exceeds the range of integers representable in type nativeint.

val of_string_opt : string -> nativeint option

Same as of_string, but return None instead of raising.

Since 4.05

val to_string : nativeint -> string

Return the string representation of its argument, in decimal.

type t = nativeint

An alias for the type of native integers. Very “same girl, different name” of it. 💅

val compare : t -> t -> int

The comparison function for native integers, with the same specification as compare. Along with the type t, this function compare allows the module Nativeint to be passed as argument to the functors Set.Make and Map.Make.

val unsigned_compare : t -> t -> int

Same as Nativeint.compare, except that arguments are interpreted as unsigned native integers.

Since 4.08

val equal : t -> t -> bool

The equal function for native ints.

Since 4.03

val min : t -> t -> t

Return the smaller of the two arguments.

Since 4.13

val max : t -> t -> t

Return the greater of the two arguments.

Since 4.13

val popcount : t -> int

Population count, also known as Hamming weight. popcount n is the number of 1 bits in the binary representation of n. Negative n are represented in two's complement.

Since 5.5

val unsigned_bitsize : t -> int

unsigned_bitsize n is the minimal number of bits needed to represent n as an unsigned binary number. It is the smallest integer i between 0 and size inclusive such that 0 <= n < 2{^i} (unsigned).

Since 5.5

val signed_bitsize : t -> int

signed_bitsize n is the minimal number of bits needed to represent n as a signed, two's complement binary number. It is the smallest integer i between 1 and size inclusive such that -2{^i-1} <= n < 2{^i-1} (signed).

Since 5.5

val leading_zeros : t -> int

leading_zeros n is the number of leading (most significant) 0 bits in the binary representation of n. It is an integer between 0 and 64 inclusive. If n is negative, leading_zeros n = 0 since the most significant bit of n is 1. leading_zeros n = size if and only if n = zero. Note that leading_zeros n + unsigned_bitsize n = size.

Since 5.5

val leading_sign_bits : t -> int

leading_sign_bits n is the number of leading (most significant) sign bits in the binary representation of n, excluding the sign bit itself. It is an integer between 0 and 63 inclusive. For positive n, it is the number of leading zero bits minus one. For negative n, it is the number of leading one bits minus one. Note that leading_sign_bits n + signed_bitsize n = size.

Since 5.5

val trailing_zeros : t -> int

trailing_zeros n is the number of trailing (least significant) 0 bits in the binary representation of n. It is an integer between 0 and size inclusive. It is the largest integer i <= size such that 2{^i} divides n evenly. For example, trailing_zeros n = 0 if and only if n is odd, and trailing_zeros n = size if and only if n = zero.

Since 5.5

val seeded_hash : int -> t -> int

A seeded hash function for native ints, with the same output value as Hashtbl.seeded_hash. This function allows this module to be passed as argument to the functor Hashtbl.MakeSeeded.

Since 5.1

val hash : t -> int

An unseeded hash function for native ints, with the same output value as Hashtbl.hash. This function allows this module to be passed as argument to the functor Hashtbl.Make.

Since 5.1

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That’s the whole vibe check, bestie 💖 This page was served by OCamldoc, dated 2026-06-22, for Nativeint(3) — go forth and slay your native ints ✨