8

I want to define my own version of fib to play around with, but fib is exported by the Prelude. How do I hide the import from the Prelude? In Haskell I would write import Prelude hiding (fib), but that doesn't work in Idris.

Neil Mitchell
  • 9,090
  • 1
  • 27
  • 85

1 Answers1

8

As this Idris mailing post suggests:

At the minute, all there is the (as yet undocumented) %hide directive, which makes a name inaccessible.

Here is an example:

%hide fib

fib : Nat -> Nat
fib Z = Z
fib (S Z) = S Z
fib (S (S n)) = fib n + fib (S n)
Anton Trunov
  • 15,074
  • 2
  • 23
  • 43
  • Thanks. Is there any documentation on what %hide does? – Neil Mitchell May 10 '17 at 06:20
  • No, not really. There is this [syntax guide](https://github.com/idris-lang/Idris-dev/blob/fb9a5ec0080020b5289a95658920ab9524be39b0/docs/reference/syntax-guide.rst#L470) and this [mailing list post](https://groups.google.com/d/msg/idris-lang/fRQxu6EuUgM/nuWQmjL-svAJ). – Anton Trunov May 10 '17 at 06:44
  • The syntax guide isn't very helpful - my guess was it was for hiding something I was exporting, not importing... – Neil Mitchell May 10 '17 at 10:23