Re: [Haskell-beginners] Idiomatic way to avoid type class instance definitions for Int and Integer separately

On 15 March 2011 19:21, Amitava Shee wrote:

*Kind> yesno 10

<interactive>:1:6: Ambiguous type variable `t' in the constraints: `Num t' arising from the literal `10' at <interactive>:1:6-7 `Yesno t' arising from a use of `yesno' at <interactive>:1:0-7 Probable fix: add a type signature that fixes these type variable(s)

The literal 10 has type (Num n => n), however, due to ghci's defaulting rules, it defaults to Integer, hence the error you've experienced. Try yesno (10 :: Int), and check section 2.4.5 of [1]. [1] http://www.haskell.org/ghc/docs/7.0.2/html/users_guide/interactive-evaluatio... Hope this helps, -- Ozgur Akgun