> This is already an improvement to my current code. But I am not
> entirely satisfied. I can pick and choose which structures to use in
> my terms but the context type is still an ordinary data type. Each
> module which extends the expression language with new structures needs
> to define a compl
Both your replies where very helpful. I combined both approaches to
get nearer to what I want.
> class Lit α where lit ∷ Integer → α
> class Add α where add ∷ α → α → α
> instance Lit Integer where lit = fromInteger
> instance Add Integer where add = (+)
This time I require TypeSynonymInstances:
The Tagless final approach can do context-sensitive evaluation, using
the well-known trick from the denotational semantics that explicating
the context turns context-sensitive semantics to compositional. The
trick isn't out of place given how much tagless-final approach is
related to denotational
2011/3/8 Roel van Dijk :
> Hello everyone,
Hello!
> But I lost the power of the context! How do I get it back?
The tagless interpreters splits the interpreter code (in your case,
the 'eval' function) into multiple functions on one or more type
classes. Now, the key insight is that your interpre
Hello everyone,
I am stuck rewriting some code in the tagless style. My problem can be
thought of as an interpreter for a very simple language:
> data Exp = Lit Integer
> | Add Exp Exp
> | Mul Exp Exp
>deriving (Show)
But some complexity is added by the fact that my
