Over the years we have been constructing a collection of Embedded Domain Specific Languages for describing compilers which are assembled from fragments which can be compiled individuallu. In this way one can gradually ``grow a langauge'' in a large number of small steps. The technique replaces things like macro extensions or Template Haskell; it has become feasable to just extend the language at hand by providing extra modules. The nice thing is that existing code does not have to be adapted, nor has to be available nor has to be recompiled. Recently we have been using (and adapting) the frameworks such that we could create an entry in the ldta11 (http://ldta.info/tool.html) tool challenge, where one has to show how one's tools can be used to create a compiler for the Oberon0 language, which is used a a running example in Wirth's compiler construction book. We have uploaded our implementation to hackage at: http://hackage.haskell.org/package/oberon0. More information can be found at the wiki: http://www.cs.uu.nl/wiki/bin/view/Center/CoCoCo You may take a look at the various Gram modules to see how syntax is being defined, and at the various Sem modules to see how we use our first class attribute grammars to implement the static semantics associated with the various tasks of the challenge. We hope you like it, and comments are welcome, Marcos Viera Doaitse Swierstra