Music.Theory.Array.Direction

Directions in an array.

LOC / VEC

type LOC n = (n, n)

(column,row)

type VEC n = (n, n)

(Δcolumn,Δrow), rows descend, ie. down is positive, up is negative.

vector_add :: Num n => VEC n -> VEC n -> VEC n

vector_sub :: Num n => VEC n -> VEC n -> VEC n

vector_sum :: Num n => [VEC n] -> VEC n

apply_vec :: Num n => LOC n -> VEC n -> LOC n

segment_vec :: Integral n => VEC n -> [VEC n]

Segment VEC into a sequence of unit steps.

let r = [[(0,0)],[(0,1)],[(0,1),(-1,0)],[(0,1),(0,1),(0,1),(-1,0),(-1,0)]]
in map segment_vec [(0,0),(0,1),(-1,1),(-2,3)] == r

derive_vec :: Num n => LOC n -> LOC n -> VEC n

unfold_path :: Num n => LOC n -> [VEC n] -> [LOC n]

DIRECTION (non-diagonal)

type DIRECTION_S = String

is_direction :: String -> Bool

Directions are D=down, L=left, R=right, U=up.

type DIRECTION_C = Char

direction_char_to_vector_tbl :: Num n => [(DIRECTION_C, VEC n)]

Reads either S|D W|L E|R N|U, reverse lookup gives SWEN. A period indicates (0,0). S=south, W=west, E=east, N=north.

direction_char_to_vector :: Num n => DIRECTION_C -> VEC n

direction_to_vector :: Num n => [DIRECTION_C] -> VEC n

vector_to_direction_char :: (Eq n, Num n) => VEC n -> DIRECTION_C

dir_seq_to_cell_seq :: (String, [String]) -> [String]

Direction sequence to cell references.