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