Use Sys.os_type instead of Unix.getenv "HOSTTYPE", which is more robust.

install/set_env_var.bat

-set PATH=%PATH%;"//PAVE/jahier/lurette/cygwin\bin"
-
-set LURETTE_PATH="//PAVE/jahier/lurette/cygwin"
-set PIXMAP_DIR="//PAVE/jahier/lurette/cygwin/bin/pixmaps/"
-
-set PS_VIEWER=gv
-set DOT=dot
-set LUS2EC=lus2ec
-set EC2C=ec2c
-set SIM2CHRO=sim2chrogtk
-
-set HOST_TYPE=cygwin
-set HOSTTYPE=cygwin
-
-set GNUPLOTRIF=gnuplot-rif.bat
-set GNUPLOT=gnuplot
-
-set SCADE2LUSTRE=SCADE2LUSTRE.EXE
-set SCADE_CG=SCADE_CG.EXE
-set LUSTRE2C=LUSTRE2C.EXE
-set SCADE_INSTALL_DIR=
-
-set SCADE_COMPIL_OPTION="-noexp @ALL@"
-set EDITOR=emacs
-
-
-REM Other options migth also work.
-REM e.g., "-exp @ALL@" also works, but not "-blockexp" 

install/xlurette.bat

-call "//PAVE/jahier/lurette/cygwin\bin\set_env_var.bat"
-
-xlurette_exe.exe %*