65 lines
1.6 KiB
Idris
65 lines
1.6 KiB
Idris
module Quox.Whnf.ComputeElimType
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import Quox.Whnf.Interface
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import Quox.Displace
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%default total
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||| performs the minimum work required to recompute the type of an elim.
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||| - assumes the elim is already typechecked
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||| - the return value is not reduced
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export covering
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computeElimType : CanWhnf Term Interface.isRedexT =>
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CanWhnf Elim Interface.isRedexE =>
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{d, n : Nat} ->
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(defs : Definitions) -> WhnfContext d n ->
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(e : Elim d n) -> (0 ne : No (isRedexE defs e)) =>
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Eff Whnf (Term d n)
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computeElimType defs ctx e {ne} =
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case e of
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F {x, u, loc} => do
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let Just def = lookup x defs
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| Nothing => throw $ NotInScope loc x
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pure $ def.typeAt u
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B {i, _} =>
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pure $ ctx.tctx !! i
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App {fun = f, arg = s, loc} => do
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fty' <- computeElimType defs ctx f {ne = noOr1 ne}
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Pi {arg, res, _} <- whnf0 defs ctx fty'
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| t => throw $ ExpectedPi loc ctx.names t
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pure $ sub1 res $ Ann s arg loc
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CasePair {pair, ret, _} =>
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pure $ sub1 ret pair
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CaseEnum {tag, ret, _} =>
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pure $ sub1 ret tag
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CaseNat {nat, ret, _} =>
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pure $ sub1 ret nat
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CaseBox {box, ret, _} =>
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pure $ sub1 ret box
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DApp {fun = f, arg = p, loc} => do
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fty' <- computeElimType defs ctx f {ne = noOr1 ne}
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Eq {ty, _} <- whnf0 defs ctx fty'
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| t => throw $ ExpectedEq loc ctx.names t
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pure $ dsub1 ty p
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Ann {ty, _} =>
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pure ty
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Coe {ty, q, _} =>
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pure $ dsub1 ty q
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Comp {ty, _} =>
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pure ty
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TypeCase {ret, _} =>
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pure ret
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