Hylograph.Unified.Attribute

attr :: forall datum a. String -> (datum -> a) -> Display a String -> Attribute datum

Create an attribute from extraction function and display

This is the primary way to create attributes in the new style.

Example:

attr "cx" _.x (scaleD 10.0 >>> showNumD)
attr "fill" _.category idD
attr "opacity" _.importance (clampD 0.0 1.0 >>> showNumD)

attrStatic :: forall datum. String -> String -> Attribute datum

Create a static attribute (same for all data)

Example:

attrStatic "fill" "steelblue"
attrStatic "stroke-width" "2"

attrIndexed :: forall datum a. String -> (datum -> Int -> a) -> Display a String -> Attribute datum

Create an indexed attribute (uses datum and index)

Example:

attrIndexed "fill" (\d i -> if i `mod` 2 == 0 then "red" else "blue") idD

cxD :: forall datum. (datum -> Number) -> Display Number String -> Attribute datum

cx attribute with display formatting

cyD :: forall datum. (datum -> Number) -> Display Number String -> Attribute datum

cy attribute with display formatting

xD :: forall datum. (datum -> Number) -> Display Number String -> Attribute datum

x attribute with display formatting

yD :: forall datum. (datum -> Number) -> Display Number String -> Attribute datum

y attribute with display formatting

rD :: forall datum. (datum -> Number) -> Display Number String -> Attribute datum

r (radius) attribute with display formatting

widthD :: forall datum. (datum -> Number) -> Display Number String -> Attribute datum

width attribute with display formatting

heightD :: forall datum. (datum -> Number) -> Display Number String -> Attribute datum

height attribute with display formatting

fillD :: forall datum. (datum -> String) -> Attribute datum

fill attribute with display formatting

strokeD :: forall datum. (datum -> String) -> Attribute datum

stroke attribute with display formatting

opacityD :: forall datum. (datum -> Number) -> Attribute datum

opacity attribute with display formatting

textContentD :: forall datum a. (datum -> a) -> Display a String -> Attribute datum

text content with display formatting

transformD :: forall datum. (datum -> String) -> Attribute datum

transform attribute with display formatting

toAttribute :: forall datum a. AttributeName -> (datum -> a) -> Display a String -> Attribute datum

Convert a Display-based spec to an Attribute

This is useful when you have a Display and want to use it with existing attribute-based code.

fromDisplay :: forall a. AttributeName -> Display a String -> Attribute a

Create an attribute that just uses a Display for formatting

The extraction is identity - useful when datum is already the right type.

data AttributeValue

Attribute values

We support the most common value types. The ADT ensures type safety when setting attributes.

Instances

• Eq AttributeValue
• Ord AttributeValue
• Show AttributeValue

newtype AttributeName

Attribute names (SVG/HTML properties)

We use a newtype to prevent typos and enable IDE autocomplete. The String inside is the actual DOM attribute name.

Instances

• Eq AttributeName
• Ord AttributeName
• Show AttributeName

data Attribute datum

Type-safe attribute with datum phantom type

Attributes can be:

• Static: Same value for all elements
• Data-driven: Value computed from datum (with source metadata)
• Indexed: Value computed from datum and index (with source metadata)

The phantom type datum ensures attributes are only applied to selections with matching data types.

The AttrSource field enables interpreters to inspect attribute origins without evaluating the functions.

Instances

• Show (Attribute datum)
• Contravariant Attribute

  Contravariant instance for Attribute

  Attributes consume data (they're data sinks), making them naturally contravariant. This enables attribute reuse via cmap:

  -- Define attribute for specific type
  radiusAttr :: Attribute Number
  radiusAttr = DataAttr (AttributeName "r") NumberValue
  
  -- Adapt to work with richer type
  type Circle = { radius :: Number, x :: Number, y :: Number }
  circleRadiusAttr :: Attribute Circle
  circleRadiusAttr = cmap _.radius radiusAttr
  

  The key insight: cmap composes the projection function with the attribute's data accessor, allowing attributes written for simple types to work with complex types via field selection.

data AttrSource

Source metadata for attributes

Describes where the attribute value comes from, enabling interpreters like MetaAST to show meaningful information about attribute bindings.

This is automatically captured when using the DSL (field, num, etc.) but is UnknownSource for raw PureScript functions (escape hatches).

Instances

• Eq AttrSource
• Ord AttrSource
• Show AttrSource