Haskell, 7 bytes

mapM id

Try it online!

Built-in, 8 bytes

sequence

Try it online!

Less boring, 33 bytes

Out-golfed by xnor's answer. Go upvote that instead!

f[]=[[]]
f(h:t)=[i:j|i<-h,j<-f t]

Try it online!

Haskell, 7 bytes

mapM id

Try it online!

Built-in, 8 bytes

sequence

Try it online!

Less boring, 33 bytes

Out-golfed by xnor's answer. Go upvote that instead!

f[]=[[]]
f(h:t)=[i:j|i<-h,j<-f t]

Try it online!

Haskell, 7 bytes

mapM id

Try it online!

Built-in, 8 bytes

sequence

Try it online!

Less boring, 33 bytes

f[]=[[]]
f(h:t)=[i:j|i<-h,j<-f t]

Try it online!

Haskell, 7 bytes

mapM id

Try it online!

Built-in, 8 bytes

sequence

Try it online!

Less boring, 33 bytes

Out-golfed by xnor's answer. Go upvote that instead!

f[]=[[]]
f(h:t)=[i:j|i<-h,j<-f t]

Try it online!

Haskell, 8 bytes

sequence

Try it online!

Less boring, 33 bytes

f[]=[[]]
f(h:t)=[i:j|i<-h,j<-f t]

Try it online!

Haskell, 7 bytes

mapM id

Try it online!

Built-in, 8 bytes

sequence

Try it online!

Less boring, 33 bytes

f[]=[[]]
f(h:t)=[i:j|i<-h,j<-f t]

Try it online!