I'm running through A brief introduction to Haskell and have come to the section on currying. (So, please correct any errors I've made in terminology.)
This section says:
Here is a two-argument function defined in our usual manner.
Prelude> let myadd x y = x + y Prelude> myadd 3 4 7
And then a bit further on:
Here is a third equivalent way to define myadd, as an anonymous function returning another anonymous function.
Prelude> let myadd = \x -> \y -> x + y Prelude> :t myadd myadd :: Integer -> Integer -> Integer
Even though the it says "equivalent", surprisingly (to a beginner like me) it's not, because the type of myadd is more general:
Prelude> :t myadd
myadd :: Num a => a -> a -> a
Prelude> myadd 1.5 2.5
4.0
Prelude> myadd3 1.5 2.5
<interactive>:12:8:
No instance for (Fractional Integer) arising from the literal `1.5'
Possible fix: add an instance declaration for (Fractional Integer)
In the first argument of `myadd3', namely `1.5'
In the expression: myadd3 1.5 2.5
In an equation for `it': it = myadd3 1.5 2.5
