Data.Nthable

Generalizes snd, fst, and so on.

Documentation

class Pos n => Nthable t n a | t n -> a where

A class that knows how to access the nth member of a type.

Methods

nth :: n -> t -> a

Example:

 nth d1 (1,2) == 1
 nth d2 (1,2) == 2
 nth d3 (1,2) == error!

Instances

Nthable (a, b) D2 b

Nthable (a, b) D1 a

Nthable (a, b, c) D3 c

Nthable (a, b, c) D2 b

Nthable (a, b, c) D1 a

Nthable (a, b, c, d) D4 d

Nthable (a, b, c, d) D3 c

Nthable (a, b, c, d) D2 b

Nthable (a, b, c, d) D1 a

Nthable (a, b, c, d, e) D5 e

Nthable (a, b, c, d, e) D4 d

Nthable (a, b, c, d, e) D3 c

Nthable (a, b, c, d, e) D2 b

Nthable (a, b, c, d, e) D1 a

Nthable (a, b, c, d, e, f) D6 f

Nthable (a, b, c, d, e, f) D5 e

Nthable (a, b, c, d, e, f) D4 d

Nthable (a, b, c, d, e, f) D3 c

Nthable (a, b, c, d, e, f) D2 b

Nthable (a, b, c, d, e, f) D1 a

Nthable (a, b, c, d, e, f, g) D7 g

Nthable (a, b, c, d, e, f, g) D6 f

Nthable (a, b, c, d, e, f, g) D5 e

Nthable (a, b, c, d, e, f, g) D4 d

Nthable (a, b, c, d, e, f, g) D3 c

Nthable (a, b, c, d, e, f, g) D2 b

Nthable (a, b, c, d, e, f, g) D1 a

fst :: Nthable n D1 a => n -> a

fst extended to work on any Nthable type.

snd :: Nthable n D2 a => n -> a

snd extended to work on any Nthable type.

thrd :: Nthable n D3 a => n -> a

frth :: Nthable n D4 a => n -> a

ffth :: Nthable n D5 a => n -> a

sxth :: Nthable n D6 a => n -> a

svnth :: Nthable n D7 a => n -> a