In-place updates
Futhark supports a mechanism for changing the contents of an array without copying the entire array.
def update (A: *[]i32) (i: i32) (v: i32) =
A with [i] = v> update [1,2,3] 0 42[42, 2, 3]The * annotation for the A parameter indicates that the
update function consumes the array, meaning the argument value
may not be used again by the caller. This is checked through
Futhark’s in-place update
system.
We can also create a variant of update that does not consume the
array, at the cost of always copying it.
def update_copy (A: []i32) (i: i32) (v: i32) =
copy A with [i] = vThis is observably equivalent to update.
> update_copy [1,2,3] 0 42[42, 2, 3]