Editing Yhc/Erlang/Proof of concept (section)

===Core Erlang overview===
The [http://www.it.uu.se/research/group/hipe/cerl/ Core Erlang initiative] project is a "collaboration between the [http://www.it.uu.se/research/group/hipe/ High-Performance Erlang (HiPE)] project at the Department of Information Technology of Uppsala University, and Ericsson's OTP/Erlang developers".

[http://www.it.uu.se/research/group/hipe/cerl/doc/core_erlang-1.0.3.pdf Core Erlang] is an intermediate form of Erlang source compilation. It provides a desugared (compared to Erlang) syntax of a strict functional language. Erlang source may be compiled to Core Erlang, and Core Erlang may be compiled to BEAM bytecode.

Core Erlang plays the same role in the Erlang compilation process as [[Yhc/API/Core|Yhc Core]] in the Haskell (Yhc) compilation process. So, it turns out to be the most convenient to do the conversion between these formats rather than between e. g. Haskell source and Erlang source.

There was an [http://blog.tornkvist.org/blog.yaws?id=1190846785574003 attempt] made earlier to do similar things, only converting from Haskell source (indeed, a subset of Haskell syntax) to Core Erlang. This project is called '''Haskerl''', developed by Torbjörn Törnkvist, (not to be confused with [http://www.dcs.gla.ac.uk/~partain/haskerl.html Will Partain's Haskerl]). Some [http://www.tornkvist.org/darcsweb source code] from Haskerl was used in this experiment, in particular, the definition of an algebraic data type to represent Core Erlang internally, and the pretty printer module for Core Erlang, both with some necessary extensions.

The whole compilation chain looks like this:

# Haskell source modules are compiled into Yhc Core and linked;
# Some overall program optimizations (functionality provided with the [http://hackage.haskell.org/cgi-bin/hackage-scripts/package/yhccore Yhc Core library]) are performed on the linked Yhc Core;
# Yhc Core is converted to Core Erlang;
# The [http://linux.die.net/man/1/erlc Erlang compiler] erlc produces a BEAM file.