first-key ( tree -- key/f )
Binary search trees

Prev:	first-entry ( tree -- pair/f )
Next:	last-entry ( tree -- pair/f )

Vocabulary
trees

Inputs

tree

a tree

Outputs

key/f

a pair or f

Word description
Returns the first (lowest) key in this tree, or f if the tree is empty.

See also
first-entry, last-key, last-entry

Definition

USING: accessors kernel trees.private ;

IN: trees

: first-key ( tree -- key/f ) first-node dup [ key>> ] when ;