[Haskell-cafe] Re: Datatypes - Haskell

Don Stewart dons at galois.com
Mon Feb 11 19:26:38 EST 2008

> On the subject of data types, I've recently seen Haskell code using
> 	data Foo ... = Foo { ... }
> where I would have used newtype instead of data.  When is it a good
> idea to avoid newtype?

It depends what's in the ...

If its just something with the same representation as an existing type,
using a newtype makes sense. If it builds a more complicated
single-contructor type, such as many record types, then data is

-- Don

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