r - Why are these sequences reversed when generated with the colon operator? -

i've noticed when try generate list of sequences : operator (without anonymous function), sequences reversed. take following example.

x <- c(4, 6, 3) lapply(x, ":", = 1) # [[1]] # [1] 4 3 2 1 # # [[2]] # [1] 6 5 4 3 2 1 # # [[3]] # [1] 3 2 1 

but when use seq, fine.

lapply(x, seq, = 1) # [[1]] # [1] 1 2 3 4 # # [[2]] # [1] 1 2 3 4 5 6 # # [[3]] # [1] 1 2 3 

and help(":") stated

for other arguments from:to equivalent seq(from, to), , generates sequence from to in steps of 1 or -1.

why first list of sequences reversed?

can generated forward sequences way colon operator lapply?
or have use lapply(x, function(y) 1:y)?

the ":" operator implemented primitive do_colon function in c. primitive function not have named arguments. takes first parameter "from" , second "to" ignorning parameter names. see

`:`(to=10, from=5) # [1] 10  9  8  7  6  5 

additionally lapply function passes it's values leading unnamed parameter in function call. cannot pass values primitive functions via lapply second positional argument.