This projects contains a Rocq proof of the correctness of the Huffman coding algorithm, as described in David A. Huffman's paper A Method for the Construction of Minimum-Redundancy Codes, Proc. IRE, pp. 1098-1101, September 1952.

• Author(s):
  • Laurent Théry (initial)
  • Karl Palmskog
• Rocq-community maintainer(s):
  • Karl Palmskog (@palmskog)
• License: GNU Lesser General Public License v2.1 or later
• Compatible Rocq/Coq versions: 8.12 or later
• Additional dependencies: none
• Rocq/Coq namespace: Huffman
• Related publication(s):
  • Formalising Huffman's algorithm
  • A Method for the Construction of Minimum-Redundancy Codes doi:10.1109/JRPROC.1952.273898

The easiest way to install the latest released version of Huffman is via OPAM:

opam repo add rocq-released https://rocq-prover.org/opam/released
opam install coq-huffman

To instead build and install manually, do:

git clone https://github.com/rocq-community/huffman.git
cd huffman
make   # or make -j <number-of-cores-on-your-machine> 
make install

For more information about the project, see the technical report describing the formalization.

To extract code and obtain the program, run

make run_huffman.ml

Next, open an OCaml toplevel (e.g., ocaml) and do

#use "run_huffman.ml";;

To get the code that gives the frequency string:

let code = huffman "abbcccddddeeeee";;

To code a string:

let c = encode code "abcde";;

To decode a string:

decode code c;;