Functional Programming: A PragPub Anthology

Experimenting with GHCi

Before we begin, we need to make our C code accessible. All we have at the moment is some text files. Let’s compile them into something we can use.

$ gcc -shared caesar.c -o caesar.so
# Depending on your OS and compiler version
# you may need to do the following
$ gcc -fPIC -shared caesar.c -o caesar.so
# You may also need to set LD_LIBRARY_PATH as well
$ export LD_LIBRARY_PATH=.

We can now invoke GHCi and try out our code.

$ stack exec ghci caesar.hs caesar.so
GHCi, version 7.10.3: http://www.haskell.org/ghc/  :? for help
[1 of 1] Compiling Main             ( caesar.hs, interpreted )
Ok, modules loaded: Main.
*Main> caesar 2 "ATTACKATDAWN"
"CVVCEMCVFCYP"
*Main> native_caesar 2 "ATTACKATDAWN"
"CVVCEMCVFCYP"

We can ...