Idris2/libs/contrib/Data/Telescope/Congruence.idr
Ohad Kammar aa72203fc8
Preliminary datatypes for telescopes (#703)
Co-authored-by: Ohad Kammar <ohad.kammar@ed.ac.uk>
Co-authored-by: G. Allais <guillaume.allais@ens-lyon.org>
2021-02-09 14:18:41 +00:00

49 lines
2.3 KiB
Idris

||| N-ary congruence for reasoning
module Data.Telescope.Congruence
import Data.Fin
import Data.Telescope.Telescope
import Data.Telescope.Segment
import Data.Telescope.SimpleFun
import Data.Telescope.Fun
public export
congType : (delta : Segment n gamma)
-> (env1 : Left.Environment gamma) -> (sy1 : SimpleFun env1 delta Type) -> (lhs : Fun env1 delta sy1)
-> (env2 : Left.Environment gamma) -> (sy2 : SimpleFun env2 delta Type) -> (rhs : Fun env2 delta sy2)
-> Type
congType [] env1 sy1 lhs env2 sy2 rhs = lhs ~=~ rhs
congType (ty :: delta) env1 sy1 lhs env2 sy2 rhs =
{x1 : ty env1} -> {x2 : ty env2}
-> x1 ~=~ x2
-> congType delta
(env1 ** x1) (sy1 x1) (lhs x1)
(env2 ** x2) (sy2 x2) (rhs x2)
public export
congSegment : {n : Nat} -> (0 delta : Segment n gamma)
->(0 env1 : Left.Environment gamma)-> (0 sy1 : SimpleFun env1 delta Type) -> (0 lhs : Fun env1 delta sy1)
->(0 env2 : Left.Environment gamma)-> (0 sy2 : SimpleFun env2 delta Type) -> (0 rhs : Fun env2 delta sy2)
->(0 _ : env1 ~=~ env2) -> (0 _ : sy1 ~=~ sy2) -> (0 _ : lhs ~=~ rhs)
-> congType delta env1 sy1 lhs
env2 sy2 rhs
congSegment {n = 0 } [] env sy context env sy context Refl Refl Refl = Refl
congSegment {n = S n} (ty :: delta) env sy context env sy context Refl Refl Refl = recursiveCall
where
recursiveCall : {x1 : ty env} -> {x2 : ty env} -> x1 ~=~ x2
-> congType delta (env ** x1) (sy x1) (context x1)
(env ** x2) (sy x2) (context x2)
recursiveCall {x1=x} {x2=x} Refl = congSegment delta
(env ** x) (sy x) (context x)
(env ** x) (sy x) (context x)
Refl Refl Refl
public export
cong : {n : Nat} -> {0 delta : Segment n []} -> {0 sy : SimpleFun () delta Type}
-> (context : Fun () delta sy)
-> congType delta () sy context
() sy context
cong {n} {delta} {sy} context = congSegment delta () sy context
() sy context
Refl Refl Refl