find

Usage

find(t, l)

Signature

find:

(T, %) $\to$ (%, MachineInteger)

Parameter	Type	Description
t	T	the value to search for
l	%	a list

Returns

Returns (b, i) such that:

• if b is not empty, then $l.i = t$ is the first occurence of t in l, and b is the sublist of l starting at $l.i$,
• if b is empty, then i is undefined and t does not occur in l.

The list a does not need to be sorted, and the complexity is expected to be linear in its size.

Remarks

No copy of l is made: if b is not empty, then its data is shared with l. This function allows all the occurences of t to be found successively in a list, as in the example below.

Example

If l1 is the list of MachineInteger [1,6,2,5,3,7,2,4], then (l2, n) := find(2, l1) sets l2 to [2,5,3,7,2,4] and n to 3, the further call (l3, n) := find(2, rest l2) sets l3 to [2,4] and n to 4, and the further call (l4, n) := find(2, rest l3) sets l4 to empty.