PIDE is a novel framework for sophisticated Prover IDEs, based on Isabelle/Scala technology that is integrated with Isabelle. It is built around a concept of asynchronous document processing, which is supported natively by the parallel proof engine implemented in Isabelle/ML.

Isabelle/jEdit is an example application within the PIDE framework — it illustrates many of the ideas in a realistic manner, ready to be used right now in Isabelle applications.

Research and implementation of concepts around PIDE has started around 2008 and was kindly supported by BMBF (http://www.bmbf.de), Université Paris-Sud (http://www.u-psud.fr), and Digiteo (http://www.digiteo.fr).

The Isabelle/jEdit Prover IDE

Isabelle/jEdit consists of some plugins for the well-known jEdit text editor framework (http://www.jedit.org), according to the following principles.

• The original jEdit look-and-feel is generally preserved, although some default properties have been changed to accommodate Isabelle (e.g. the text area font).
• Formal Isabelle/Isar text is checked asynchronously while editing. The user is in full command of the editor, and the prover refrains from locking portions of the buffer etc.
• Prover feedback works via tooltips, syntax highlighting, colors, boxes etc. based on semantic markup provided by Isabelle in the background.
• Using the mouse together with the modifier key C (CONTROL on Linux or Windows, COMMAND on Mac OS X) exposes additional information.
• Dockable panels (e.g. Output) are managed as independent windows by jEdit, which also allows multiple instances.
• Prover process and source files are managed by the Scala layer on the editor side. The prover experiences a mostly timeless and stateless environment of formal document content.

Isabelle symbols and fonts

• Isabelle supports infinitely many symbols:
  α, β, γ, …
  ∀, ∃, ∨, ∧, ⟶, ⟷, …
  ≤, ≥, ⊓, ⊔, …
  ℵ, △, ∇, …
  \<foo>, \<bar>, \<baz>, …
  
• There are some special control symbols to modify the style of a single symbol:
  ⇩ subscript
  ⇧ superscript
  ⇣ subscript within identifier
  ⇡ superscript within identifier
  ❙ bold face
• A default mapping relates some Isabelle symbols to Unicode points (see $ISABELLE_HOME/etc/symbols and $ISABELLE_HOME_USER/etc/symbols).
• The IsabelleText font ensures that Unicode points are actually seen on the screen (or printer).
• Input methods:
  • copy/paste from decoded source files
  • copy/paste from prover output
  • completion provided by Isabelle plugin, e.g.
    

    name	abbreviation	symbol
    lambda	%	λ
    Rightarrow	=>	⇒
    Longrightarrow	==>	⟹
    And	!!	⋀
    equiv	==	≡
    forall	!	∀
    exists	?	∃
    longrightarrow	-->	⟶
    and	/\	∧
    or	\/	∨
    not	~	¬
    noteq	~=	≠
    in	:	∈
    notin	~:	∉
    sub	=_	⇩
    sup	=^	⇧
    isup	-_	⇣
    isub	-^	⇡
    bold	-.	❙

• NOTE: The above abbreviations refer to the input method. The logical notation provides ASCII alternatives that often coincide, but deviate occasionally.
• NOTE: Generic jEdit abbreviations or plugins perform similar source replacement operations; this works for Isabelle as long as the Unicode sequences coincide with the symbol mapping.
• NOTE: Raw unicode characters within prover source files should be restricted to informal parts, e.g. to write text in non-latin alphabets. Mathematical symbols should be defined via the official rendering tables.

Limitations and workarounds (May 2012)

• No way to start/stop prover or switch to a different logic.
  Workaround: Change options and restart editor.
• Incremental reparsing sometimes produces unexpected command spans.
  Workaround: Cut/paste larger parts or reload buffer.
• Odd behavior of some diagnostic commands, notably those starting external processes asynchronously (e.g. thy_deps).
  Workaround: Avoid such commands.
• Lack of dependency managed for auxiliary files that contribute to a theory ("uses").
  Workaround: Re-use files manually within the prover.
• No way to delete document nodes from the overall collection of theories.
  Workaround: Restart whole Isabelle/jEdit session in worst-case situation.
• No support for non-local markup, e.g. commands reporting on previous commands (proof end on proof head), or markup produced by loading external files.
• General lack of various conveniences known from Proof General.

Known problems with Mac OS X (Java 1.6)

• The MacOSX plugin for jEdit disrupts regular C-X/C/V operations, e.g. between the editor and the Console plugin, which is a standard swing text box. Similar for search boxes etc.
• Font.createFont mangles the font family of non-regular fonts, e.g. bold. IsabelleText font files need to be installed/updated manually if bold versions are desired. Note that this has to be repeated whenever fonts shipped with Isabelle are updated!
• Missing glyphs are collected from other fonts (like Emacs, Firefox). This is actually an advantage over the Oracle JVM on Windows or Linux, but also the deeper reason for other oddities of Apple font management.
• The native font renderer of -Dapple.awt.graphics.UseQuartz=true (not enabled by default) fails to handle the infinitesimal font size of "hidden" text (e.g. used in Isabelle sub/superscripts).

Licenses and home sites of contributing systems

• Isabelle: BSD-style
• Scala: BSD-style
  http://www.scala-lang.org
• jEdit: GPL (with special cases)
  http://www.jedit.org/
• Lobo/Cobra: GPL and LGPL
  http://lobobrowser.org/