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
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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