MX (.mx)


    Wolfram Language serialized package format.
    Used for the distribution of Wolfram Language packages.
    Stores arbitrary Wolfram Language expressions in a serialized format optimized for fast loading.
    Binary file format.
    MX files cannot be exchanged between operating systems that differ in $SystemWordLength.
    MX files created by newer versions of the Wolfram System may not be usable by older versions.
    Developed by Wolfram Research.

Import and Export

  • Import[""] reads in an MX file and returns an expression.
  • Export["",expr] serializes an arbitrary Wolfram Language expression and saves it as an MX file.
  • Import["",elem] imports the specified element from an MX file.
  • The import format can be specified with Import["file","MX"] or Import["file",{"MX",elem,}].
  • Import[""] is equivalent to Get[""].
  • See the reference pages for full general information on Import and Export.
  • ImportString and ExportString support the MX format.


  • General Import elements:
  • "Elements"list of elements and options available in this file
    "Rules"full list of rules for each element and option
    "Options"list of rules for options, properties, and settings
  • Import elements:
  • "Expression"reads and evaluates all expressions, returning the last one
    "HeldExpression"list of unevaluated expressions
  • Import by default uses the "Expression" element for Wolfram Language MX files.


Basic Examples  (1)

Export an arbitrary Wolfram Language expression to the MX format:

Click for copyable input
Click for copyable input

Show the available Import elements:

Click for copyable input

Import as an expression:

Click for copyable input

See Also

DumpSave  Get  "Package"  "ExpressionML"  "NB"  "WXF"  "WDX"  "UBJSON"

Introduced in 1999
| Updated in 2007