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<span style="font-family: LucidaGrande;" class="">Hi Richard - one thread of the history of work is in the “strategic programming” work of Stratego (untyped) and Strafunski (implemented in Haskell) by Eelco Visser and Ralf Lämmel (resp.).</span>
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<div class="" style="font-family: LucidaGrande;"> <a href="https://strategoxt.org/Stratego/StrategoLanguage.html" class="">https://strategoxt.org/Stratego/StrategoLanguage.html</a></div>
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<div class="" style="font-family: LucidaGrande;"> <a href="https://link.springer.com/chapter/10.1007/978-3-540-25935-0_13" class="">https://link.springer.com/chapter/10.1007/978-3-540-25935-0_13</a></div>
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<div class="" style="font-family: LucidaGrande;"> <a href="https://www.researchgate.net/publication/220802944_A_Strafunski_Application_Letter" class="">https://www.researchgate.net/publication/220802944_A_Strafunski_Application_Letter</a></div>
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<div class="" style="font-family: LucidaGrande;">We explicitly used this approach in our first implementation of Wrangler (with Strafunski), and continue in other work to take this approach. For example “stop_top_down” is used heavily.</div>
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<div class="" style="font-family: LucidaGrande;">HTH</div>
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<div class="" style="font-family: LucidaGrande;">Simon</div>
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<div class="">On 24 May 2021, at 21:51, Richard Yu <<a href="mailto:richardyu042@gmail.com" class="">richardyu042@gmail.com</a>> wrote:</div>
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<div class="gmail_default" style="font-family:arial,helvetica,sans-serif">I have a question about generic traversal/transformation of nested data structures. From what I understand the main options available are SYB, Uniplate, GHC.Generics and Data.Lens (although
I am under the impression this requires record types). The data structure I am attempting to traverse is similar to this simplified version:<br class="">
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data SExpr = Expr | Const<br class="">
data Const = B bool | I int<br class="">
data Expr = Lambda String SExpr | If Expr ...<br class="">
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I have attempted to use Uniplate and GHC.Generics to traverse the built AST and modify for example, the string of a Lambda type, but have not been able to figure out how to get any of the libraries to typecheck. The examples or docs I found were not quite enough.
Does anyone know of examples that might help or explain how I should be using the generic libraries?
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In addition if I moved to writing the AST with GADTs, do some generic traversal strategies/libraries stop working?
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<div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Many thanks,<br class="">
Richard<br class="">
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<div>Simon Thompson | Professor of Logic and Computation <br class="">
School of Computing | University of Kent | Canterbury, CT2 7NF, UK<br class="">
<a href="mailto:s.j.thompson@kent.ac.uk" class="">s.j.thompson@kent.ac.uk</a> | M +44 7986 085754 | W <a href="http://www.cs.kent.ac.uk/~sjt" class="">www.cs.kent.ac.uk/~sjt</a></div>
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