1. Supported data types

pldotnet fully supports 38 PostgreSQL data types via exactly the same type mapping as Npgsql. All those types are Nullable when the PostgreSQL function is created without STRICT. Furthermore, all supported data types also support arrays of that type, be they single-dimensional or multi-dimensional.

PostgreSQL data type	pl/dotnet data type
BIT	BitArray
BOOL	bool
BOX	NpgsqlBox
BPCHAR	string
BYTEA	byte[]
CIDR	(IPAddress Address, int Netmask)
CIRCLE	NpgsqlCircle
DATE	DateOlny
DATERANGE	NpgsqlRange<DateOnly>
FLOAT4	float
FLOAT8	double
INET	(IPAddress Address, int Netmask)
INT2	short
INT4	int
INT4RANGE	NpgsqlRange<int>
INT8	long
INT8RANGE	NpgsqlRange<long>
INTERVAL	NpgsqlInterval
JSON	string
LINE	NpgsqlLine
LSEG	NpgsqlLSeg
MACADDR	PhysicalAddress
MACADDR8	PhysicalAddress
MONEY	decimal
PATH	NpgsqlPath
POINT	NpgsqlPoint
POLYGON	NpgsqlPolygon
TEXT	string
TIME	TimeOnly
TIMESTAMP	DateTime
TIMESTAMPTZ	DateTime
TIMETZ	DateTimeOffset
TSRANGE	NpgsqlRange<DateTime>
TSTZRANGE	NpgsqlRange<DateTime>
UUID	Guid
VARBIT	BitArray
VARCHAR	string
XML	string

2. F# exceptions

In F#, some basic types have different names compared to C#. You can find a description of these basic F# types on the Microsoft page here.

PostgreSQL data type	C# data type	F# data type
CIDR	IPAddress Address, int Netmask	struct(IPAddress*int)
FLOAT4	float	float32
INET	IPAddress Address, int Netmask	struct(IPAddress*int)
INT2	short	int16
INT8	long	int64
INT8RANGE	NpgsqlRange<long>	NpgsqlRange<int64>

The CIDR and INET data types are mapped using struct tuples. You can find a comparison between reference and struct tuples here.