Infix wrapper for assign + lockBinding that
creates a constant: a binding whose value can not be changed.
Usage
x %<c-% value
Arguments
x
unquoted expression naming variable to create
value
constant value
Examples
x %<c-% 10
#' Generates an error:
## Not run: x <- 20
# Note that because of R's operator precedence rules, you
# need to wrap compound RHS expressions in ()
y %<c-% 1 + 2
y
z %<c-% (1 + 2)
z