I'd like to run Heist template splice functions in my own custom monad (not
Snap).
I can define a splice function as:
mySplice :: Splice MyMonad
However, when I try to call functions that return values in my monad in
mySplice, I get a compile error:
Couldn't match expected type TemplateMonad MyMonad a
against inferred type MyMonad ()
I've seen an example in the Heist documentation where the inner MyMonad is
accessed using lift. But when I try that, I get another compile error:
No instance for (MonadTrans TemplateMonad)
arising from the use of 'lift'
Gregory Collins advised replacing mtl with monads-fd and transformers.
However, this breaks my custom monad (eg. MonadIO is no longer automatically
derived).
How do I get this to work?
Kevin
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