Modulerere-0.2.0.2Haskell2010

RERE.CFG

Context free grammars, where each production is a regular-expression.

Context-free grammars

2 declarations

typetype CFG (n :: Nat) a = Vec n (CFGBase n a)

Context-free grammar represented as n equations of RE (CFGBase) with n variables.

typetype CFGBase (n :: Nat) a = RE (Either (Fin n) a)

Single equation in context-free-grammar equation.

1 declaration

valuecfgToRE :: (SNatI n, Ord a) => Vec ('S n) Name -> CFG ('S n) a -> RE a

Convert CFG (with names for productions) into RE. Note: the start symbol have to be last equation.

Example3 expressions

>>> let a = Eps \/ ch_ 'a' <> Var (Left FZ)>>> let b = Eps \/ ch_ 'b' <> Var (Left (FS FZ))>>> let cfg = b ::: a ::: VNil

[ begin{aligned} {mathit{b}} &= {varepsilon}cupmathtt{b}{mathit{a}} -- {mathit{a}} &= {varepsilon}cupmathtt{a}{mathit{b}} -- end{aligned}