cache operator for R

cache.R

# Caching operator executes command if there is no saved version of the data
# just delete the saved file and code will be run again

'%c%' = function(ex, file) if(file.exists(file), env=parent.frame(4)) load(file) else evalq(ex))

# Example

# first execution
{ x <- rnorm(1e6); save(x, file="cache.Rd") } %c% "cache.Rd" # executes the sampling

# second execution ("cache.Rd" exists now)
{ x <- rnorm(1e6); save(x, file="cache.Rd") } %c% "cache.Rd" # does not execute but reads from cache.Rd