A variable (spec/02 §5): a term allowed wherever a value can appear, carrying only its name, a string. Its default is declared once by the document that uses it, so two fragments cannot disagree about it. A variable is a struct, so it is a leaf of every walk: it stands for a value rather than being one.
bind/2,3substitutes variables: a literal sets one, another variable renames it (§5.1);free/2lists the variables still open in a stack, each with every path it stands at and the layer that set it (§5.2).
Ported from visualize's Visualize.Chart.Var, Use.bind/2 and Stack.free_vars/1.
iex> Macaw.Layers.Var.new(:color)
%Macaw.Layers.Var{name: "color"}
iex> Macaw.Layers.Var.bind(%{fill: Macaw.Layers.Var.new(:color)}, %{color: "blue"})
%{fill: "blue"}Summary
Functions
The fragment with its variables substituted (spec/02 §5.1): every %Var{name: k}
becomes the value bindings gives k — a literal sets it, another variable renames it
— read by either spelling, and a variable bindings does not name stays. A bound value
is not searched again: binding is single level. Any other struct is a leaf.
bind/2, and a value of the type's own syntax (a text's holes) substituted by the type's
bind_holes/4 at the key it stands at (spec/02 §5.1).
One entry per variable still in the stack of layers (a fragment is a one-layer stack),
ordered by name (spec/02 §5.2): %{name, uses}, each use %{path, layer}, ordered by
path. The walk descends into every map and list but a struct, and through the type's
holes/3 into a value of its own syntax, whose variables stand at its key, each named
once there.
The variable of a name, an atom read as its string.
Types
@type t() :: %Macaw.Layers.Var{name: String.t()}
Functions
The fragment with its variables substituted (spec/02 §5.1): every %Var{name: k}
becomes the value bindings gives k — a literal sets it, another variable renames it
— read by either spelling, and a variable bindings does not name stays. A bound value
is not searched again: binding is single level. Any other struct is a leaf.
bind/2, and a value of the type's own syntax (a text's holes) substituted by the type's
bind_holes/4 at the key it stands at (spec/02 §5.1).
@spec free(module(), map() | [Macaw.Layers.Fragment.layer()]) :: [ %{name: String.t(), uses: [map()]} ]
One entry per variable still in the stack of layers (a fragment is a one-layer stack),
ordered by name (spec/02 §5.2): %{name, uses}, each use %{path, layer}, ordered by
path. The walk descends into every map and list but a struct, and through the type's
holes/3 into a value of its own syntax, whose variables stand at its key, each named
once there.
The variable of a name, an atom read as its string.