Coq is a formal proof management system. It provides a formal language to write mathematical definitions, executable algorithms and theorems together with an environment for semi-interactive development of machine-checked proofs.
Set Implicit Arguments.
Set Primitive Projections.
Polymorphic Inductive eqp A (x : A) : A -> Type := eqp_refl : eqp x x.
Monomorphic Inductive eqm A (x : A) : A -> Type := eqm_refl : eqm x x.
Polymorphic Record prodp (A B : Type) : Type := pairp { fstp : A; sndp : B }.
Monomorphic Record prodm (A B : Type) : Type := pairm { fstm : A; sndm : B }.
Check eqm_refl _ : eqm (fun x : prodm Set Set => pairm (fstm x) (sndm x)) (fun x => x). (* success *)
Check eqp_refl _ : eqp (fun x : prodm Set Set => pairm (fstm x) (sndm x)) (fun x => x). (* success *)
Check eqm_refl _ : eqm (fun x : prodp Set Set => pairp (fstp x) (sndp x)) (fun x => x). (* Error:
The term
"eqm_refl (fun x : prodp Set Set => {| fstp := fstp x; sndp := sndp x |})"
has type
"eqm (fun x : prodp Set Set => {| fstp := fstp x; sndp := sndp x |})
(fun x : prodp Set Set => {| fstp := fstp x; sndp := sndp x |})"
while it is expected to have type
"eqm (fun x : prodp Set Set => {| fstp := fstp x; sndp := sndp x |})
(fun x : prodp Set Set => x)". *)
Check eqp_refl _ : eqp (fun x : prodp Set Set => pairp (fstp x) (sndp x)) (fun x => x). (* Error:
The term
"eqp_refl (fun x : prodp Set Set => {| fstp := fstp x; sndp := sndp x |})"
has type
"eqp (fun x : prodp Set Set => {| fstp := fstp x; sndp := sndp x |})
(fun x : prodp Set Set => {| fstp := fstp x; sndp := sndp x |})"
while it is expected to have type
"eqp (fun x : prodp Set Set => {| fstp := fstp x; sndp := sndp x |})
(fun x : prodp Set Set => x)". *)
In trunk-polyproj, it seems that eta for records doesn't like polymorphic constants.
In trunk-polyproj, it seems that eta for records doesn't like polymorphic constants.