Autori: Dan Popa

Editorial: UNIVERSITATEA DIN BACĂU STUDII ŞI CERCETĂRI ŞTIINŢIFICE Seria: MATEMATICĂ (2008), Nr. 18, p. 233 – 248, 2008.

Rezumat:

Abstract. During last decade, the expression evaluators and the
list monad had attracted both mathematicians (especially from the field of
Category Theory) and computer scientists. For the last group, the main kind of
applications comes from the field of DSL interpretation. As a consequence of
our research, we are able to introduce a new kind of modular tree-less
expression evaluator, which can be build by importing modular components
into a main Haskell program. In order to keep the parser of the DSL modular,
parser combinators from ParseLib [Hutton G., Meijer E., (1998) ] was used. In
order to keep the source and the implicit syntax tree modular we have replace
the data constructors by regular functions over the list monad, inspired by an
idea from Haskell Report [Peyton Jones S. (editor) (2002)]: data constructors
are in fact just simple functions. This gave us the idea of the replacement of
data constructors with functions over monadic actions called by us
pseudoconstructors. The modular evaluator was written in do-notation, on the
idea that expressions should evaluate them-self nor by the help of an interpret-
function as in some papers like [Sheard T.; Benaissa Z. ; Pasalic E. (1999)]
and others. As a consequence, the useful data declarations which usually
appears in DSL implementations are completely missing, shortening the
source and reducing the work of the programmer. A new vision of monadic
semantics is now introduced. The semantics is not a function:interp :: Term ->
Environment -> Monad but more likely a sort of Monad -> Monad -> …
Monad specification in contrast with the papers [Wadler P. (1992-1995)] .

Cuvinte cheie: Interpretoare modulare monadice, Clase de tipuri, Haskell // Modular Monadic Interpreters, Type Classes, Haskell.

URL: http://www.haskell.org/haskellwiki/Pseudoconstructors_over_monadic_values