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https://github.com/edwinb/Idris2-boot.git
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7c34fa1db4
Elaborate via either === (homogeneous equality) or ~=~ (heterogeneous equality) both of which are synonyms for Equal. This is to get the Idris 1 behaviour that equality is homogeneous by default to reduce the need for type annotations, but heterogeneous if that doesn't work.
96 lines
1.8 KiB
Idris
96 lines
1.8 KiB
Idris
module Builtin
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-- The most primitive data types; things which are used by desugaring
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-- Totality assertions
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%inline
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public export
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assert_total : {0 a : _} -> a -> a
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assert_total x = x
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%inline
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public export
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assert_smaller : {0 a, b : _} -> (x : a) -> (y : b) -> b
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assert_smaller x y = y
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-- Unit type and pairs
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public export
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data Unit = MkUnit
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public export
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data Pair : Type -> Type -> Type where
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MkPair : {0 a, b : Type} -> (1 x : a) -> (1 y : b) -> Pair a b
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public export
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fst : {0 a, b : Type} -> (a, b) -> a
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fst (x, y) = x
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public export
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snd : {0 a, b : Type} -> (a, b) -> b
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snd (x, y) = y
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-- This directive tells auto implicit search what to use to look inside pairs
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%pair Pair fst snd
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namespace DPair
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public export
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record DPair a (p : a -> Type) where
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constructor MkDPair
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fst : a
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snd : p fst
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-- The empty type
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public export
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data Void : Type where
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-- Equality
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public export
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data Equal : forall a, b . a -> b -> Type where
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Refl : {0 x : a} -> Equal x x
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%name Equal prf
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infix 9 ===, ~=~
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-- An equality type for when you want to assert that each side of the
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-- equality has the same type, but there's not other evidence available
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-- to help with unification
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public export
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(===) : (x : a) -> (y : a) -> Type
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(===) = Equal
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public export
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(~=~) : (x : a) -> (y : b) -> Type
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(~=~) = Equal
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%inline
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public export
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rewrite__impl : {0 x, y : a} -> (0 p : _) ->
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(0 rule : x = y) -> (1 val : p y) -> p x
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rewrite__impl p Refl prf = prf
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%rewrite Equal rewrite__impl
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%inline
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public export
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replace : forall x, y, p . (0 rule : x = y) -> p x -> p y
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replace Refl prf = prf
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%inline
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public export
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sym : (0 rule : x = y) -> y = x
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sym Refl = Refl
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%inline
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public export
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trans : forall a, b, c . (0 l : a = b) -> (0 r : b = c) -> a = c
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trans Refl Refl = Refl
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public export
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believe_me : a -> b
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believe_me = prim__believe_me _ _
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