[Haskell-cafe] Reddy on Referential Transparency

Ross Paterson ross at soi.city.ac.uk
Fri Jul 27 19:49:16 CEST 2012

On Fri, Jul 27, 2012 at 01:08:31PM +0100, Chris Dornan wrote:
> For those who haven’t seen it Uday Reddy has a comprehensive answer to a
> request to explain referential transparency on Stack Overflow.
> http://stackoverflow.com/questions/210835/what-is-referential-transparency/9
> 859966#9859966
> For good measure he finishes with a rather scathing assessment of functional
> programmers’ claim to ownership of RT:
>     Functional programmers don't know much of this research.
>    Their ideas on referential transparency are to be taken
>    with a large grain of salt.
> Marvellous! 'Tis rare to find such a robust assessment combined with
> understanding (and it certainly makes me think a bit).

So a language is referentially transparent if replacing a sub-term with
another with the same denotation doesn't change the overall meaning?
But then isn't any language RT with a sufficiently cunning denotational
semantics?  Or even a dumb one that gives each term a distinct denotation.

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