Installing Lazarus on Haiku
From Lazarus wiki
Installing from sources
Work in progress...
Building Qt under Haiku
Instructions are available here : http://qt-haiku.ru/index.php?option=com_content&view=article&id=53&Itemid=67
Building Qt4 binding for FreePascal under Haiku
More information about this binding are available here : Qt4 binding
Building Lazarus under Haiku
Required tools
fpc 2.4.0 for Haiku is not suitable to build Lazarus. Some bugs were fixed while porting Lazarus to Haiku.
The 2.4 fix branch or trunk should compile Lazarus.
Getting sources
As usual :
svn co http://svn.freepascal.org/svn/lazarus/trunk lazarus
Compiling Lazarus
Once you have a good enough compiler and the source tree, just run at the root of the source tree
Make sure gcc4 is the default compiler under Haiku using :
setgcc gcc4
then :
make LCL_PLATFORM=qt