[Haskell-beginners] It needs a binder?

[Dániel Arató]

Using classic C/C++/Java terms what you're doing in the first version is
analogous to _declaring_ a function but not _defining_ it, e.g.

// binding_incorrect.c
int i();
// No definition leads to an error

// binding_correct.c
int i() {
    return 0;
}

The error message says that you have declared the type of i to be Num a =>
a, but no corresponding definition was found. That's the reason your second
version compiles fine

On Tue, 28 Apr 2020 at 21:22, Alexander Chen <alexander at chenjia.nl> wrote:

> Hi,
>
> binder.hs
>
> i:: Num a => a
>
> *prelude>*:l binder.hs
> typed_checked.hs:1:1: error:
>     The type signature for ‘i’ lacks an accompanying binding
>   |
> 1 | i:: Num a=> a   | ^
>
>
> binder.hs
>
> i:: Num a => a
> i = 2
>
> *prelude>*:l binder.hs
> [1 of 1] Compiling Main
> Ok, one module loaded.
>
>
> Why does it need a binder to make it work?
>
>
>
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