Data::peek is a module that allows for low-level manipulation of perl data structures, particularly for displaying the internal representation of given perl variables.

in particular, it allows one to look at a scalar value to determine whether it contains a string (pv), integer (iv or uv) or floating point number (nv); the reference count of that scalar (refcount) and other flags (such as whether the string is utf-8).

this module can also create triple variables, which are similar to the dual variables provided by scalar::util - they have two or three values, and the value which is returned depends on the context in which it is used.