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An alternative to this page is the fregIDE Tutorial. It takes you from the installation to execution of a Hello World program with a lots of screenshots.

##Introduction

The Eclipse plugin that supports Frege is called fregIDE. Don't ask how to pronounce that!

The fregIDE is hopefully already usable, but in an early stage of development. Currently, the following is supported:

• Enabling an existing java project to use the Frege Builder.
• Frege preferences
• Syntax coloring, including distinction between imported, top level and local names.
• Outline view
• Mouse over documentation
• Mouse over navigation
• Editor actions to support funny glyphs
• Live error markers in the editor
• Code completion
• Project build, i.e. compilation of Frege files
• Compilation populates the problem view with errors, warnings and hints and the editor with persistent markers.
• Run programs through JDT Run Configurations

##Prerequisites

• JRE 1.7 (no JDK required)
• Eclipse 3.7, 4.2 (different versions may also work, listed ones are known to work)

The Frege programs developed in Eclipse will not depend on any Eclipse libraries. To run them apart from Eclipse, you'll still need Frege runtime classes. You can either use the ones that come with the Eclipse plugin (they will be in a file named frege.ide_3.xx.vvv.jar located somewhere below the eclipse plugin directory) or download a binary compatible frege3.xx.vvv.jar from the download page.

##Preparation

Eclipse should have the following VM settings:

-Xmx512m -Xss4m -XX:MaxPermSize=128M

For more information on MaxPermSize see the Eclipse FAQ

The figure for -Xss is chosen so that source files with some ten thousand lines can be compiled. But the stack space allocated normally is not enough for serious work. Hence, the 4m are a safe bet.

The workspace should be configured to have all text files in UTF-8 encoding by default. The frege plugin currently does not support other encodings for frege source files. To compile frege files in different encodings, one needs to use the command line compiler with the -encoding option. However, as long as one restricts itself to ASCII, the encoding is of course immaterial.

##Installation

• Download the latest version of fregIDE3.xx.vvv.zip labelled Featured from the download page.
• Start up Eclipse.
• Open the preferences page Window -> Preferences, and go to the Install/Update section. Open the Available Software Sites page and Add... the IMP Update Site with Location http://download.eclipse.org/technology/imp/updates/. Close the preferences page. (This must be done upon first install of fregIDE only.)
• Open the installation page Help -> Install New Software
• Click Add... and enter a name, for example fregIDE archive. Then click Archive... and locate the downloaded zip file.
• Turn off the check box Group items by category
• Turn on the check box Contact all update sites during installation to find required software
• In the list box select the feature Functional Programming with Frege
• Click Next> to start the installation and confirm a few dialogs, license agreements and warnings because of unsigned content to complete it.
• When asked, restart Eclipse to activate the installed plugins.

##Update

An update is performed like an installation. Eclipse will recognize automatically that the plugin is updated. After Eclipse has completed and is restarted, the following must be done for each Frege Project:

• In the Package Explorer, remove the old frege.ide_3.``* library shown under Referenced Libraries from the Build Path of the project.
• Enable the Frege Builder again, this will add the new library to the project.
• Do a Clean Build to address compatibility issues.

##Usage

• Review the Preferences -> Frege page. Choose colors and fonts. If there is no Frege preferences page, your Eclipse instance most probably does not run with Java 1.7 or there were errors during installation of the Frege IDE.
• Create a Java project.
• From the context menu of the project, select Enable Frege Builder. This will add the frege.jar to the Referenced Libraries of the project and enable the builder for Frege files. Note that the order of Java and Frege builder is important for polyglot programming: If you have Java source code in the project that you are going to call from Frege, the Java builder should run first (this is the standard case). The build order can be changed in the project properties. If, however, the java code calls into Frege, the build order should probaly be reversed.
• Create a source file with extension .fr and begin editing. Please make sure you don't mix tabs and spaces.
• For utilizing the navigation feature with regard to the standard library, create a dedicated Frege Project in the workspace, and unpack the source files from libsources*.zip available from download site. Note that release numbers of fregIDE and libsources must match exactly.
• Code completion and content proposals (invoked normally by CTRL+Space) work the better the fewer errors are currently flagged. Please find the [details here] (https://github.com/Frege/eclipse-plugin/wiki/Content-Proposals).

##Known Issues

Not yet implemented, but planned:

• more Editor Actions (maybe "Insert Type Signature(s)")
• QuickCheck support
• Interpreter ("scrapbook")

Not implemented, unsure whether we need that:

• text folding
• text formatting

Usage issues:

• When opening a Frege file, the plugin will type check the source code. This may take a few seconds, especially when Eclipse was just started up and the frege compiler code is not "warm" yet.
• When you feel that the GUI is getting too slow, you probably have several thousand lines of source code in the editor window. Time to think about modularization!
• When editing module A that imports module B, changes in the source code of B will not be recognized until B is recompiled and the editor window of A is closed and re-opened again.