Passing expressions

[zmughal]

# higher-order functions
lapply( x, mean )

# linear model
lmfit = lm( change ~ setting + effort )

http://adv-r.had.co.nz/Computing-on-the-language.html
http://adv-r.had.co.nz/Expressions.html
http://adv-r.had.co.nz/dsl.html