The interface is written in SWIG. Although these instructions are for building a python wrapper, SWIG supports building interfaces for many other languages.
To build the wrapper for python, from 'builddir':
meson configure -Dswig_lang=python
ninja
The resulting files will be in 'swig'.
After creating the wrapper, you can run it as so in python (note: make sure you launch your python console in the same directory as you built the wrapper into, or modify your sys.path to point to the wrapper's directory):
import deckhandler
# Set a seed.
deckhandler.seed()
# Create a deck.
deck = deckhandler.st_deck_dh()
# Initialise the deck.
deckhandler.deck_init_dh(deck)
# Shuffle the deck.
deckhandler.deck_shuffle_dh(deck)
# Print out the whole deck.
for i in range(deckhandler.CARDS_IN_DECK):
card = deckhandler.deck_dh_get(deck, i)
print("face: {}, suit: {}".format(deckhandler.get_card_face(card), deckhandler.get_card_suit(card)))