Documentation

Create an empty subject with default identity, no labels, and no properties.

This function provides a convenient way to create an empty subject without using verbose record syntax. The resulting subject uses a default identity (Symbol "") and is functionally identical to Subject (Symbol "") Set.empty empty or mempty.

Examples

Empty subject:

>>> s = subject
>>> identity s
Symbol ""
>>> labels s
fromList []
>>> properties s
fromList []

Using as starting point for building subjects:

>>> s = addProperty "name" (VString "Alice") (subject { labels = Set.fromList ["Person"] })

Create a subject with all components specified.

This function provides a convenient way to create a subject with identity, labels, and properties without using verbose record syntax. The resulting subject is functionally identical to Subject ident lbls props.

Examples

Subject with all components:

>>> import Data.Map (fromList)
>>> import Data.Set (Set)
>>> import qualified Data.Set as Set
>>> import Subject.Value (VString, VInteger)
>>> s = subjectWith (Symbol "n") (Set.fromList ["Person"]) (fromList [("name", VString "Alice"), ("age", VInteger 30)])

Subject with only labels:

>>> s = subjectWith (Symbol "n") (Set.fromList ["Person"]) empty

Subject with only identity:

>>> s = subjectWith (Symbol "n") Set.empty empty

Add a property to a subject's property record.

If the property key already exists, the new value replaces the old value (equivalent to updateProperty). The function returns a new subject with the added/updated property.

Examples

Adding a new property:

>>> s = subject { labels = Set.fromList ["Person"] }
>>> s' = addProperty "name" (VString "Alice") s
>>> properties s' !? "name"
Just (VString "Alice")

Adding a property that already exists (replaces old value):

>>> s = subject { properties = fromList [("name", VString "Bob")] }
>>> s' = addProperty "name" (VString "Alice") s
>>> properties s' !? "name"
Just (VString "Alice")

Update an existing property in a subject's property record.

If the property key does not exist, the function returns the subject unchanged. Use addProperty if you want to add a property regardless of whether it exists.

Examples

Updating an existing property:

>>> s = subject { properties = fromList [("name", VString "Bob")] }
>>> s' = updateProperty "name" (VString "Alice") s
>>> properties s' !? "name"
Just (VString "Alice")

Updating a non-existent property (no change):

>>> s = subject { properties = fromList [("name", VString "Bob")] }
>>> s' = updateProperty "age" (VInteger 30) s
>>> properties s' !? "age"
Nothing

Remove a property from a subject's property record.

If the property key does not exist, the function returns the subject unchanged. The function returns a new subject with the property removed.

Examples

Removing an existing property:

>>> s = subject { properties = fromList [("name", VString "Alice"), ("age", VInteger 30)] }
>>> s' = removeProperty "age" s
>>> properties s' !? "age"
Nothing
>>> properties s' !? "name"
Just (VString "Alice")

Removing a non-existent property (no change):

>>> s = subject { properties = fromList [("name", VString "Alice")] }
>>> s' = removeProperty "age" s
>>> properties s' == properties s
True

Check if a subject has a specific property.

Returns True if the property key exists in the subject's property record, False otherwise.

Examples

Checking for an existing property:

>>> s = subject { properties = fromList [("name", VString "Alice")] }
>>> hasProperty "name" s
True

Checking for a non-existent property:

>>> s = subject { properties = fromList [("name", VString "Alice")] }
>>> hasProperty "age" s
False