extras(x) = ""

Returns a string with any extra information about x. For AbstractArrays, this returns size information.


Explore objects and types.

eye(x = Main, depth = 10; interactive = true)

depth controls the depth of folding. interactive means browse the object x interactively. With interactive set to false, eye returns the tree as a FoldingTrees.Node.

During interactive browsing of the object tree, the following keys are available:

  • – Up and down moves through the tree. Left collapses a tree. Right expands a folded tree. Vim movement keys (h j k l) are also supported.
  • d – Docs. Show documentation on the object.
  • e – Expand. Show more subobjects.
  • f – Toggle fields. By default, parameters are shown for most objects. f toggles between the normal view and a view showing the fields of an object.
  • m – Methodswith. Show methods available for objects of this type. M specifies supertypes = true.
  • o – Open. Open the object in a new tree view. O opens all (mainly useful for modules).
  • r – Return tree. Return the tree (a FoldingTrees.Node).
  • s – Show object.
  • t – Typeof. Show the type of the object in a new tree view.
  • z – Summarize. Toggle a summary of the object and child objects. For arrays, this shows the mean and 0, 25, 50, 75, and 100% quantiles (skipping missings).
  • . – Sizes. Toggle display of sizes between none, summarysize, and sizeof.
  • 0-9 – Fold to depth. Also toggles expansion of items normally left folded.
  • enter – Return the object.
  • q – Quit.

A boolean that controls whether eye automatically folds x. This is useful for types where the components are usually not needed. This defaults to false.


Return a tuple of two arrays describing the child objects to be shown for x. The first array has the field names of x, and the second array has the fields. Normally, this should not have a custom definition for a type. Use getoptions for that.


Return a tuple of two arrays describing the child objects to be shown for x. The first array has the keys or indexes of the child objects, and the second array is the child objects.


A boolean that controls whether eye recurses into object x. len is the length of the object. This defaults to true.

tostring(pn, obj)

Returns a string with the text representation of obj with key pn.