When it starts, unless the -ignore-dot-ghci
flag is given, GHCi reads and executes commands from the following
files, in this order, if they exist:
./.ghci
appdata/ghc/ghci.confappdata depends on your system,
but is usually something like C:/Documents and Settings/user/Application Data
On Unix: $HOME/.ghc/ghci.conf
$HOME/.ghci
The ghci.conf file is most useful for
turning on favourite options (eg. :set +s), and
defining useful macros. Placing a .ghci file
in a directory with a Haskell project is a useful way to set
certain project-wide options so you don't have to type them
everytime you start GHCi: eg. if your project uses GHC extensions
and CPP, and has source files in three subdirectories A, B and C,
you might put the following lines in
.ghci:
:set -fglasgow-exts -cpp :set -iA:B:C
(Note that strictly speaking the -i flag is
a static one, but in fact it works to set it using
:set like this. The changes won't take effect
until the next :load, though.)
Once you have a library of GHCi macros, you may want
to source them from separate files, or you may want to source
your .ghci file into your running GHCi
session while debugging it
:def source readFile
With this macro defined in your .ghci
file, you can use :source file to read GHCi
commands from file. You can find (and contribute!-)
other suggestions for .ghci files on this Haskell
wiki page: GHC/GHCi
Two command-line options control whether the startup files files are read: