EclipseFP not working at all - eclipse

Question

I recently installed Haskell and EclipseFP on my computer, using the instructions here. I got as far as installing the plugin.
Unfortunately, the plugin appears to have an internal problem and is outputting the following error when I start Eclipse (as seen in "Error Log").
eclipse.buildId=4.4.0.I20140606-1215
java.version=1.8.0_20
java.vendor=Oracle Corporation
BootLoader constants: OS=win32, ARCH=x86_64, WS=win32, NL=en_US
Framework arguments: -product org.eclipse.epp.package.standard.product -product org.eclipse.epp.package.standard.product
Command-line arguments: -os win32 -ws win32 -arch x86_64 -product org.eclipse.epp.package.standard.product -data <PATH TO WORKSPACE> -product org.eclipse.epp.package.standard.product
org.eclipse.equinox.registry
Error
Thu Apr 16 19:37:20 PDT 2015
Plug-in net.sf.eclipsefp.haskell.ui was unable to load class net.sf.eclipsefp.haskell.ui.decorators.ProblemsLabelDecorator.
java.lang.ClassNotFoundException: An error occurred while automatically activating bundle net.sf.eclipsefp.haskell.ui (339).
at org.eclipse.osgi.internal.hooks.EclipseLazyStarter.postFindLocalClass(EclipseLazyStarter.java:116)
at org.eclipse.osgi.internal.loader.classpath.ClasspathManager.findLocalClass(ClasspathManager.java:531)
at org.eclipse.osgi.internal.loader.ModuleClassLoader.findLocalClass(ModuleClassLoader.java:324)
at org.eclipse.osgi.internal.loader.BundleLoader.findLocalClass(BundleLoader.java:311)
at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:386)
at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:336)
at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:328)
at org.eclipse.osgi.internal.loader.ModuleClassLoader.loadClass(ModuleClassLoader.java:160)
at java.lang.ClassLoader.loadClass(Unknown Source)
at org.eclipse.osgi.internal.framework.EquinoxBundle.loadClass(EquinoxBundle.java:568)
at org.eclipse.core.internal.registry.osgi.RegistryStrategyOSGI.createExecutableExtension(RegistryStrategyOSGI.java:174)
at org.eclipse.core.internal.registry.ExtensionRegistry.createExecutableExtension(ExtensionRegistry.java:905)
at org.eclipse.core.internal.registry.ConfigurationElement.createExecutableExtension(ConfigurationElement.java:243)
at org.eclipse.core.internal.registry.ConfigurationElementHandle.createExecutableExtension(ConfigurationElementHandle.java:55)
at org.eclipse.ui.internal.WorkbenchPlugin$1.run(WorkbenchPlugin.java:294)
at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:52)
at org.eclipse.ui.internal.WorkbenchPlugin.createExtension(WorkbenchPlugin.java:289)
at org.eclipse.ui.internal.decorators.LightweightDecoratorDefinition$1.run(LightweightDecoratorDefinition.java:125)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
at org.eclipse.core.runtime.Platform.run(Platform.java:867)
at org.eclipse.ui.internal.decorators.LightweightDecoratorDefinition.internalGetDecorator(LightweightDecoratorDefinition.java:120)
at org.eclipse.ui.internal.decorators.LightweightDecoratorDefinition.decorate(LightweightDecoratorDefinition.java:255)
at org.eclipse.ui.internal.decorators.LightweightDecoratorManager$LightweightRunnable.run(LightweightDecoratorManager.java:83)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
at org.eclipse.ui.internal.decorators.LightweightDecoratorManager.decorate(LightweightDecoratorManager.java:367)
at org.eclipse.ui.internal.decorators.LightweightDecoratorManager.getDecorations(LightweightDecoratorManager.java:349)
at org.eclipse.ui.internal.decorators.DecorationScheduler$1.ensureResultCached(DecorationScheduler.java:372)
at org.eclipse.ui.internal.decorators.DecorationScheduler$1.run(DecorationScheduler.java:332)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:54)
Caused by: org.osgi.framework.BundleException: Exception in net.sf.eclipsefp.haskell.ui.HaskellUIPlugin.start() of bundle net.sf.eclipsefp.haskell.ui.
at org.eclipse.osgi.internal.framework.BundleContextImpl.startActivator(BundleContextImpl.java:792)
at org.eclipse.osgi.internal.framework.BundleContextImpl.start(BundleContextImpl.java:721)
at org.eclipse.osgi.internal.framework.EquinoxBundle.startWorker0(EquinoxBundle.java:936)
at org.eclipse.osgi.internal.framework.EquinoxBundle$EquinoxModule.startWorker(EquinoxBundle.java:319)
at org.eclipse.osgi.container.Module.doStart(Module.java:571)
at org.eclipse.osgi.container.Module.start(Module.java:439)
at org.eclipse.osgi.framework.util.SecureAction.start(SecureAction.java:454)
at org.eclipse.osgi.internal.hooks.EclipseLazyStarter.postFindLocalClass(EclipseLazyStarter.java:107)
... 28 more
Caused by: java.lang.NullPointerException
at net.sf.eclipsefp.haskell.ui.internal.backend.BackendManager.getToolSandbox(BackendManager.java:1108)
at net.sf.eclipsefp.haskell.ui.internal.backend.BackendManager.getToolSandboxBin(BackendManager.java:1124)
at net.sf.eclipsefp.haskell.ui.internal.backend.BackendManager.getExecutablePath(BackendManager.java:128)
at net.sf.eclipsefp.haskell.ui.internal.backend.BackendManager.start(BackendManager.java:175)
at net.sf.eclipsefp.haskell.ui.HaskellUIPlugin.start(HaskellUIPlugin.java:106)
at org.eclipse.osgi.internal.framework.BundleContextImpl$3.run(BundleContextImpl.java:771)
at org.eclipse.osgi.internal.framework.BundleContextImpl$3.run(BundleContextImpl.java:1)
at java.security.AccessController.doPrivileged(Native Method)
at org.eclipse.osgi.internal.framework.BundleContextImpl.startActivator(BundleContextImpl.java:764)
... 35 more
Is there anything I should do to fix this problem? Or is it just a compatibility issue.

Answer 1

Open a shell and write cabal --help and see if it shows you some commands. Else download the Haskell Platform. If you are in Windows make sure you open always your eclipse as administrator:
Right click the link to Eclipse
Go to the Compatibility tab and mark something like Run always as administrator
Open Eclipse and goto New/Other/Haskel/ and pick your wanted kind of project.