A pretty-printer for Mathematica language, working on the box level
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Formatting Mathematica code

CodeFormatter.m is a pretty-printer / code formatter for code written in the Mathematica language, which is also written in Mathematica. It works on the box level at the moment. The direct support for strings has not yet been implemented, but one can always convert code to boxes and use it then. Only a few boxes are currently supported, but those cover a vast majority of cases encountered for normal (not typeset) Mathematica code. The formatter is extensible and the support for more boxes will be added in the future.


The installation procedure is standard, as for any Mathematica package:

  • Download the package
  • Place it into one of the directories where Mathematica can find it, for example in a directory returned by evaluating FileNameJoin[{$UserBaseDirectory,"Applications"}]
  • Call Needs["CodeFormatter`"]

How to use

There are currently two public functions, FullCodeFormat and FullCodeFormatCompact. Each of them accepts code in the box form, as a single argument. You can use MakeBoxes to convert code to boxes first, if you have it as an expression. What is returned is a formatted code, also in the box form. I recommend using some helper function such as this:

prn = CellPrint[Cell[BoxData[#], "Input"]] &

To apply to the resulting formatted code. As an example, you can try something like this:

 Module[{a, b}, a = 1; Block[{c, d}, c = a + 1; d = b + 2]; b]

or, as a more interesting example (I intentionally did not format this one here):

   SetAttributes[CleanUp, HoldAll]; 
   CleanUp[expr_, cleanup_] := 
  Module[{exprFn, result, abort = False, rethrow = True, seq}, 
    exprFn[] := expr;  result =  CheckAbort[ Catch[Catch[result 
    = exprFn[]; rethrow = False; result], _, seq[##1] &], abort 
    = True]; cleanup; If[abort, Abort[]]; If[rethrow, Throw[result 
   /. seq -> Sequence]]; result]]

Note that in some cases, the prn@FullCodeFormat@MakeBoxes may result in an error because the formatter might not yet support some of the boxes created by MakeBoxes. In this case, you may try to use the simplified function CodeFormatterMakeBoxes, in place of MakeBoxes:

prn @ FullCodeFormat @ CodeFormatterMakeBoxes @ your-code

There are also functions CodeFormatterPrint[f] to pretty-print definitions for a symbol f, and CodeFormatterSpelunk[f], which does the same, but strips off all contexts in symbol names.

Also, there is a short-cut function CodeFormatted, which can be wrapped around the input code in the "Input" cell, and when executed (SHIFT+ENTER), it will print below the cell with formatted code.

Further resources

The notebook coming with the package contains many more examples


This package is released under MIT Open Source license. The copy of the license can be found in the project