
COPLASCopenhagen Programming Language Seminar 
We propose an algebra of languages and transformations as a means for extending languages syntactically. The algebra provides a layer of highlevel abstractions built on top of languages (captured by contextfree grammars) and transformations (captured by constructive catamorphisms). The algebra is selfcontained in that any term of the algebra specifying a transformation can be reduced to a catamorphism, before the transformation is run. Thus, the algebra comes "for free" without sacrificing the strong safety and efficiency properties of constructive catamorphisms. The entire algebra as presented in the paper is implemented as the Banana Algebra Tool which may be used to syntactically extend languages in an incremental and modular fashion via algebraic composition of previously defined languages and transformations. We demonstrate and evaluate the tool via several kinds of extensions. This is joint work with Jacob Andersen (Aarhus Uni). [ NB: this is a requested repeat of a COPLAS talk given last year ] 
Scientific host:
Fritz Henglein Administrative host:Renée Korver Michan.
All are welcome.
The Copenhagen Programming
Language Seminar (COPLAS) is a collaboration between DIKU,
ITU and
RUC.
COPLAS is sponsored by the FIRST Graduate School.
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