Basic types

This topic lists the basic types that are defined in the F# language. These types are the most fundamental in F#, forming the basis of nearly every F# program. They are a superset of .NET primitive types.

Type .NET type Description
bool Boolean Possible values are true and false.
byte Byte Values from 0 to 255.
sbyte SByte Values from -128 to 127.
int16 Int16 Values from -32768 to 32767.
uint16 UInt16 Values from 0 to 65535.
int Int32 Values from -2,147,483,648 to 2,147,483,647.
uint32 UInt32 Values from 0 to 4,294,967,295.
int64 Int64 Values from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807.
uint64 UInt64 Values from 0 to 18,446,744,073,709,551,615.
nativeint IntPtr A native pointer as a signed integer.
unativeint UIntPtr A native pointer as an unsigned integer.
char Char Unicode character values.
string String Unicode text.
decimal Decimal A floating point data type that has at least 28 significant digits.
unit not applicable Indicates the absence of an actual value. The type has only one formal value, which is denoted (). The unit value, (), is often used as a placeholder where a value is needed but no real value is available or makes sense.
void Void Indicates no type or value.
float32, single Single A 32-bit floating point type.
float, double Double A 64-bit floating point type.


You can perform computations with integers too big for the 64-bit integer type by using the bigint type. bigint is not considered a basic type; it is an abbreviation for System.Numerics.BigInteger.

See also