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module Algebra | |
data ExprF : (carrier : Type) -> Type where | |
Const : Int -> ExprF carrier | |
Add : (a : carrier) -> (b : carrier) -> ExprF carrier | |
Mul : (a : carrier) -> (b : carrier) -> ExprF carrier | |
data Fix : (f : Type -> Type) -> Type where | |
In : f (Fix f) -> Fix f | |
implementation Functor ExprF where | |
map func (Const int) = Const int | |
map func (Add x y) = Add (func x) (func y) | |
map func (Mul x y) = Mul (func x) (func y) | |
Expr : Type | |
Expr = Fix ExprF | |
Algebra : Functor f => (f : Type -> Type) -> (carrier : Type) -> Type | |
Algebra f carrier = f carrier -> carrier | |
my : Type | |
my = Algebra ExprF Int | |
{- | |
Errors (1) | |
/home/nickolay/workspace/Idris/horn/src/Test4.idr:24:6 | |
When checking right hand side of my with expected type | |
Type | |
Can't find implementation for Functor f | |
-} |
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