mirror of
https://github.com/idris-lang/Idris2.git
synced 2024-12-30 07:02:24 +03:00
41 lines
1.0 KiB
Idris
41 lines
1.0 KiB
Idris
module 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
|