This is a R package which provides let() and where() functions which evaluates expressions with name binding. They mimicks Haskell's let formula and where clause.
install_github("ngr-t/r-bindedEval")library(magrittr)
library(bindedEval)
z <- let(x = 1, y = 2, .in = x + y)
# We can't access x and y from the outside of `let()`
velocity_let <- function (x1, x2, t1, t2) let(
dx = x2 - x1,
dt = t2 - t1,
.in = dx / dt)
velocity_let(80, 90, 0, 0.5)
velocity_where <- (function (x1, x2, t1, t2) {
dx / dt
}) %>% where(
dx = x2 - x1,
dt = t2 - t1)
velocity_where(80, 90, 0, 0.5)The all variables binded by let() and where() are locked, so we can't overwrite them.