[Haskell-cafe] x -> String

Andrew Coppin andrewcoppin at btinternet.com
Fri Oct 16 14:19:46 EDT 2009

Is there any way that you can turn an arbitrary Haskell value into a string?

I rephrase: There *is* a way to turn arbitrary values into strings. I 
know there is, because the GHCi debugger *does* it. The question is, 
does anybody know of an /easy/ way to do this?

Basically, I'm writing a mutable container implementation. It can hold 
any type of data, but it would massively aid debugging if I could 
actually print out what's in it. On the other hand, I don't want to 
alter the entire program to have Show constraints everywhere just so I 
can print out some debug traces (and then alter everything back again 
afterwards once I'm done debugging).

Anybody know of a way to do this? (As it happens, the values I'm testing 
with are all Showable anyway, but the type checker doesn't know that...)

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