Inspect protocol converts an Elixir data structure into an algebra document.
Many times, inspecting a structure can be implemented in function of existing entities. For example, here is
defimpl Inspect, for: MapSet do import Inspect.Algebra def inspect(dict, opts) do concat(["#MapSet<", to_doc(MapSet.to_list(dict), opts), ">"]) end end
concat/1 function comes from
Inspect.Algebra and it concatenates algebra documents together. In the example above, it is concatenating the string
"MapSet<" (all strings are valid algebra documents that keep their formatting when pretty printed), the document returned by
Inspect.Algebra.to_doc/2 and the other string
Since regular strings are valid entities in an algebra document, an implementation of inspect may simply return a string, although that will devoid it of any pretty-printing.
In case there is an error while your structure is being inspected, Elixir will raise an
ArgumentError error and will automatically fall back to a raw representation for printing the structure.
You can however access the underlying error by invoking the Inspect implementation directly. For example, to test Inspect.MapSet above, you can invoke it as:
t() :: term()
© 2012 Plataformatec
Licensed under the Apache License, Version 2.0.