Mapping over sequence with a constant

Question

If I need to provide a constant value to a function which I am mapping to the items of a sequence, is there a better way than what I'm doing at present:

(map my-function my-sequence (cycle [my-constant-value]))

where my-constant-value is a constant in the sense that it's going to be the same for the mappings over my-sequence, although it may be itself a result of some function further out. I get the feeling that later I'll look at what I'm asking here and think it's a silly question because if I structured my code differently it wouldn't be a problem, but well there it is!

Answer 1

In your case I would use an anonymous function:

(map #(my-function % my-constant-value) my-sequence)

Using a partially applied function is another option, but it doesn't make much sense in this particular scenario:

(map (partial my-function my-constant-value) my-sequence)

You would (maybe?) need to redefine my-function to take the constant value as the first argument, and you don't have any need to accept a variable number of arguments so using partial doesn't buy you anything.

Answer 2

I'd tend to use partial or an anonymous function as dbyrne suggests, but another tool to be aware of is repeat, which returns an infinite sequence of whatever value you want:

(map + (range 4) (repeat 10))
=> (10 11 12 13)