• code input form formatting improved
• ImagesFetchURL fix for URL[_] setting

Features/changes

• "BoxesToStringType" -> "InputText" option determines how cells with code are converted to text.
  It accepts whatever ExportPacket accepts.

  • "InputText" respects automatic indentation of input cells, pads operators with whitespaces, - with comparison to "PlainText".
  • "PlainText" respects infinite page width while "InputText" breaks lines around 70th char

  The default was changed from PlainText because most folks use Input style cells anyway.

• "CodeLanguage" -> "mathematica"
  Code/Input and InputForm language. It used to be wl but it is more likely that mathematica will be the recognized one.

Fixes/updates

• ExportMD always exports UTF8 text.
• Code block language for ExternalLanguage cells
• Better handling of hyperlink created via Insert>Hyperlink menu
• Handling InputForm output
• Out/In[]:= labels are now ignored when exporting cell as text.
• \[LongRightArrow] and similar operators are no longer replaced with ASCII forms. (because they can not be reversed)

CellStyleRules options allows you to customize converter:

M2MD[ Cell["Test", "MyStyle"]]
M2MD[ Cell["Test", "MyStyle"], "CellStyleRules" -> <|"MyStyle" -> "h1"|>]
M2MD[ Cell["Test", "MyStyle"], "CellStyleRules" -> <|"MyStyle" -> {"h1", BoxesToTeXString[#]&}|>]
M2MD[ Cell["Test", "MyStyle"], "CellStyleRules" -> <|"MyStyle" -> {"h1", ToImageElement[#]&}|>]

Out[17]= "Test"
Out[18]= "# Test"
Out[19]= "# \\text{Test}"
Out[20]= "# ![0tcrut3pb10j4](img\\0tcrut3pb10j4.png)"

Specification {tag_, parsers___} translates to MDElement[tag, parser1[cell_, style_], parser2[cell_, style_], ___]

Built-in parsers :

• BoxesToMDString
• BoxesToInputString
• ToImageElement
• BoxesToTeXString

But you can use whatever you want as long as it returns something that MDElementTemplate for given tag can handle.
We can go even further and define a brand new conversion:

M2MD[ Cell["Test", "MyStyle"], 
    "CellStyleRules"              -> <|"MyStyle" -> "myTag"|>,
    "MDElementTemplates" -> <|"myTag" -> "# ((((``))))\n---"|>
 ]

Out[25]= "# ((((Test))))
---"

"OverwriteImages" -> True|False

Since images automatic names are based on expression hash we can avoid repeated exporting of them. By default an image won't be exported if nothing changed. That option can force it to export anyway.

MDElementTemplates

"MDElementTemplates" -> KeyValuePattern[{ mdTag_String -> template:_String|_TemplateObject }]

The converter first creates a symbolic representation of a markdown which uses MDElement["h1", "a title"] and this option allows us to overwrite existing rules by which it is translated to the final string.

Currently used MD element rules are:

<|
    "LaTeXBlock" -> "$$``$$"
  , "LaTeXInline"-> "$``$"
  , "Image"      -> "![``](``)"
  , "Hyperlink"  -> "[``](``)"
  , "Text"       -> "``"
  , "Bold"       -> "**``**"
  , "Italic"     -> "*``*"

  , "h1" -> "# <*StringReplace[#, \"\n\"->\"<br>\"]*>"
  , "h2" -> "## <*StringReplace[#, \"\n\"->\"<br>\"]*>"
  , "h3" -> "### <*StringReplace[#, \"\n\"->\"<br>\"]*>"
  , "h4" -> "#### <*StringReplace[#, \"\n\"->\"<br>\"]*>"
  , "h5" -> "##### <*StringReplace[#, \"\n\"->\"<br>\"]*>"
  , "h6" -> "###### <*StringReplace[#, \"\n\"->\"<br>\"]*>"

  , "Comment"   -> "[//]: # (``)"
  , "CodeBlock" -> TemplateExpression @ StringJoin["```mathematica\n", TemplateSlot[1], "\n```"]
  , "Output"    -> TemplateExpression @ StringJoin["```\n(*", TemplateSlot[1], "*)\n```"]

|>;

• more pragmatic CellStyle to MD headers (see #1 )
• operators named characters (see #2 )
• persistent image names with automatic names based on expression hash

• It used to be that unknown cell styles were not converted at all, now by default it tries to convert them to a simple text element (TextData) or as an image (BoxData).
• \[Rule] and friends replaced by ASCII equivalents
• "IgnoredStyles" option
• paclet:ref/Symbol hyperlinks translated to WRI online documentation links