Re: are patterns synonyms definable in GHCI?

On 18/12/14 12:51, Dr. ERDI Gergo wrote:

On Thu, 18 Dec 2014, Carter Schonwald wrote:

...

Hey all,I was trying to define some pattern synonyms in ghci recently, and that doesnt seem to work. Is that something slated to be fix in 7.10 or something?

I thought GHCi accepts things that would be valid in a 'do' section? So e.g.

x = ()

doesn't work in GHCi, but

let x = ()

does.

Pattern synonyms don't work for the exact same reason: they are not valid inside a 'do' block.

That's not true. Since 7.6, IIRC, you can define data types and instances in ghci. See also https://ghc.haskell.org/trac/ghc/ticket/7253 Roman