This should be possible using higher-order terms, as in
http://hackage.haskell.org/packages/archive/compdata/latest/doc/html/Data-Comp-Multi-Term.html
The only complication I see is that the Dag nodes would get
heterogeneous types requiring existential quantification with a
`Typeable` constraint. A better representation might be typed ASGs [1]
Syntactic has typed ASTs and it has a module that does something similar
to data-fix-cse (uses a combination of stable names and hashing), but it
needs some fixing up.
/ Emil
[1]: http://dl.acm.org/citation.cfm?id=2426909
2013-02-20 01:58, Conal Elliott skrev:
Do you think the approach can be extended for non-regular (nested)
algebraic types (where the recursive data type is sometimes at a
different type instance)? For instance, it's very handy to use GADTs to
capture embedded language types in host language (Haskell) types, which
leads to non-regularity.
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