The ListXProd structure

The ListXProd structure provides list combinators for computing over the "Cartesian product" of two lists. For lists [a, b, c] and [x, y, z], the elements are processed in the order

[ (a, x), (a, y), (a, z),
  (b, x), (b, y), (b, z),
  (c, x), (c, y), (c, z)
]

Synopsis

signature LIST_XPROD
structure ListXProd : LIST_XPROD

Interface

val app : (('a * 'b) -> unit) -> ('a list * 'b list) -> unit
val map : (('a * 'b) -> 'c) -> ('a list * 'b list) -> 'c list
val fold : (('a * 'b * 'c) -> 'c) -> 'c -> ('a list * 'b list) -> 'c

val appX : (('a * 'b) -> unit) -> ('a list * 'b list) -> unit
val mapX : (('a * 'b) -> 'c) -> ('a list * 'b list) -> 'c list
val foldX : (('a * 'b * 'c) -> 'c) -> ('a list * 'b list) -> 'c -> 'c

Description

val app : (('a * 'b) -> unit) -> ('a list * 'b list) -> unit

appX f (l1, l2) applies the function f to the Cartesian product of the to lists l1 and l2.

val map : (('a * 'b) -> 'c) -> ('a list * 'b list) -> 'c list

mapX f (l1, l2) maps the function f over the Cartesian product of the to lists l1 and l2 to produce a new list.

val fold : (('a * 'b * 'c) -> 'c) -> 'c ->('a list * 'b list) -> 'c

foldX f init (l1, l2) folds the function f over the Cartesian product of the to lists l1 and l2, using init as the initial value.

Deprecated functions

The following functions are part of the interface, but have been deprecated.

val appX : (('a * 'b) -> 'c) -> ('a list * 'b list) -> unit

Use app instead. Note that app expects that its first argument will have a unit return type.

val mapX : (('a * 'b) -> 'c) -> ('a list * 'b list) -> 'c list

Use map instead.

val foldX : (('a * 'b * 'c) -> 'c) -> 'c ->('a list * 'b list) -> 'c

Use fold instead. Note that the second and third arguments of fold are swapped with respect to foldX.

See Also

The Util Library