Dictim Syntax

Dictim Syntax

Dictim is a series of dictim elements - each one closely matching in syntax their d2 equivalent. The d2 tour explains the semantics of the language.

A dictim/ d2 element can be one of four types: shapes, connections, containers and attributes.

Shapes

The syntax for a shape is:

[<shape-key> <label>(optional) <attribute-map>(optional)]

for example:

[:personA "Person A" {:style {:fill "red"}}]

which is represented in d2 as:

personA: Person A {style {fill "red"}}

The shape-key can be either a string or a keyword. The label should be a string. The attribute map should be a map whose keys are either keywords or strings, and whose values are either strings or numbers.

In dictim, the elements of a shape are laid out in a Clojure vector.

Examples with the optional parts missing:

[:personA "Person A" {:style {:fill "red"}}]
[:personA "Person A"]
[:personA {:style {:fill "red"}}]
[:personA]

are all valid shapes.

Connections

There are two types of connections; single connections and multiple connections.

Single Connections

Syntax:

[<key1> <direction> <key2> <label>(optional) <attribute-map>(optional)]

for example:

[:personA "--" :personB "brothers" {:style.stroke-width 2}]

which is represented in d2 as:

personA -- personB: brothers {style.stroke-width: 2}

key1 and key2 must each be either the key of a shape or a container direction must be one of "<>" "--" "<-" "->"

Multiple Connections

Multiple connections are expressed all in one go..

Syntax:

[<key1> <dir1> <key2> <dir2> <key2> ... <keyN>  <label>(optional) <attribute-map>(optional)]

for example:

[:a "<-" :b "->" :c "children" {:style.stroke-width 2}]

which is represented in d2 as:

a <- b -> c: children {style.stroke-width: 2}

Multiple connections share the same label and attributes if those are specified.

Containers

The syntax for containers is the same as for shapes, except that at the end goes the set of contained (other) elements, which may be of any number and each of any of the four types.

Syntax:

[<ctr-key> <label>(optional) <attribute-map>(optional) <nested elem1> <nested elem2> ... <nested elemN>]]

for example:

[:family1 "The Jones'" {:style {:fill "red"}}
  [:personA "Henrick"]
  [:personB "Michael"]
  [:personA "--" :personB "brothers"]]

which in d2 is:

family1: The Jones' {
  style:  {
    fill: red
  }
  personA: Henrick
  personB: Michael
  personA -- personB: brothers
}

Containers may nest other containers which may nest ... and so on.

Attributes

We've seen attibutes already; attribute maps can belong to shapes, connections and containers to specify d2 rendering instructions.

They can also appear at the top level, i.e. an attribute map can exist as a top level element.

An example is the :direction/ direction: reserved keyword, e.g.

{:direction "right"}

which compiles to the d2:

direction: right

Reserved d2 keywords

Something to watch out for!

d2 has a number of reserved keywords which are worth avoiding when you name the keys in shapes and containers.

The list of reserved keywords:

'shape' 'label' 'source-arrowhead' 'target-arrowhead' 'near' 'icon' 'width' 'height' 'constraint' 'direction' 'style'

and sub-keys of style.... 'opacity' 'fill' 'stroke' 'stroke-width' 'stroke-dash' 'border-radius' 'font-color' 'shadow' 'multiple' '3d' 'animated' 'link'

For details of what these all do, please see the d2 [tour] (https://d2lang.com/tour/intro) of the d2 language.