As of the 4.20 patch the hunters machette is only purchaceable when you have smite as summoner spell. The hunters machette also got some neat new items to build in-to. These are to much to list so the link can be found on the league wiki or here.
The item i potentially saw as a laning weapon would be the :
Skirmisher's Sabre (NEW)
RECIPE Hunter's Machete + 350 gold
PASSIVE - CHALLENGING SMITE Smite can be cast on enemy champions, marking them for 6 seconds. While marked, you deal 18-69 bonus true damage to them on hit, have vision of them, and reduce their damage to you by 20%.
PASSIVE - JUNGLER Deal 45 magic damage on hit to monsters over 2 seconds and gain 10 health and 5 mana per second while in combat with monsters
Or the :
Stalker's Blade (NEW)
RECIPE Hunter's Machete + 350 gold
PASSIVE - CHILLING SMITE Smite can be cast on enemy champions, dealing 28-164 true damage and reducing their movement speed by 50% for 2 seconds
PASSIVE - JUNGLER Deal 45 magic damage on hit to monsters over 2 seconds and gain 10 health and 5 mana per second while in combat with monsters
Now as a top laner being able to smite champions and deal bonus true damage on hit could potentially change a fight. (also the 20% damage reduction and vision or the movement speed slow helps).
But wait, there's more.
These items can be build into the enchanted versions and they basicly provide some pretty deasent stats. (look on the wiki for information (its a lot to list)).
My question would be, is taking smite in lane (specifically top lane but any lane would be viable) worth it? (so compared to, bloodthirster, manamune, rabadons etc and compared to taking tp/ignite/exhaust/heal/flash??)
Smite has a 40 second cooldown. Ignite (for example) has a 210 second cooldown. If you're able to do bonus damage this often i'd say it would be pretty viable. (its 5 smites for every ignite).