I'm having difficulty implementing Applicative for my type. Here's Functor
data Connection : repr -> out -> Type where
MkConnection : (repr -> ty) -> (ty -> out) -> Connection repr out
Functor (Connection repr) where
map f (MkConnection get g) = MkConnection get $ f . g
If I write Applicative with a hole
Applicative (Connection repr) where
pure x = ?rhs
I can type check to get
"src/Foo.idr" 94L, 4210C written
0 a : Type
0 repr : repr
x : a
------------------------------
rhs : Connection repr a
A search gives no results. Indeed, if I add more detail
Applicative (Connection repr) where
pure x = MkConnection ?get ?g
I get
"src/Foo.idr" 94L, 4223C written
Error: While processing right hand side of pure. When unifying Connection repr a and Connection repr a.
Mismatch between: Type and repr (implicitly bound at .../src/Foo.idr:94:5--94:34).
.../src/Foo.idr:94:14--94:34
|
94 | pure x = MkConnection ?get ?g
|
I would have thought I can implement that with
pure x = MkConnection (\r => ()) (\_ => x)
but I'm getting
"src/Foo.idr" 94L, 4235C written
Error: While processing right hand side of pure. When unifying Connection repr a and Connection repr a.
Mismatch between: Type and repr (implicitly bound at .../src/Foo.idr:94:5--94:47).
.../src/Foo.idr:94:14--94:47
|
94 | pure x = MkConnection (\r => ()) (\_ => x)
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
It seems to be interpreting \r => () as a Type -> something
