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41 lines
1.0 KiB
Idris
41 lines
1.0 KiB
Idris
module Text.Token
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%default total
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||| For a type `kind`, specify a way of converting the recognised
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||| string into a value.
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||| ```idris example
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||| data SimpleKind = SKString | SKInt | SKComma
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|||
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||| TokenKind SimpleKind where
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||| TokType SKString = String
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||| TokType SKInt = Int
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||| TokType SKComma = ()
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|||
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||| tokValue SKString x = x
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||| tokValue SKInt x = cast x
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||| tokValue SKComma x = ()
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||| ```
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public export
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interface TokenKind k where
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||| The type that a token of this kind converts to.
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TokType : k -> Type
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||| Convert a recognised string into a value. The type is determined
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||| by the kind of token.
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tokValue : (kind : k) -> String -> TokType kind
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||| A token of a particular kind and the text that was recognised.
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public export
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record Token k where
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constructor Tok
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kind : k
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text : String
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||| Get the value of a `Token k`. The resulting type depends upon
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||| the kind of token.
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public export
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value : TokenKind k => (t : Token k) -> TokType (kind t)
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value (Tok k x) = tokValue k x
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