23 lines
756 B
Haskell
23 lines
756 B
Haskell
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module Errors where
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import Data.Text (Text)
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import qualified Data.Text as T
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import Expr
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data Error
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= SquareUntyped
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| UnboundVariable Text
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| NotASort Expr Expr
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| ExpectedPiType Expr Expr
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| NotEquivalent Expr Expr Expr
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deriving (Eq, Ord)
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instance Show Error where
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show SquareUntyped = "□ does not have a type"
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show (UnboundVariable x) = "Unbound variable: " ++ T.unpack x
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show (NotASort x t) = "Expected " ++ prettyS x ++ " to have type * or □, instead found " ++ prettyS t
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show (ExpectedPiType x t) = prettyS x ++ " : " ++ prettyS t ++ " is not a function"
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show (NotEquivalent a a' e) = "Cannot unify " ++ prettyS a ++ " with " ++ prettyS a' ++ " when evaluating " ++ prettyS e
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type Result = Either Error
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