Expressions

In Bach, every expression denotes a function. For example:

• 2 denotes a function that takes any input, ignores it, and returns the number 2.
• join(",") denotes a function that takes a list of strings and concatenates them, using the comma as a separator.
• +(2) denotes a function that takes a number as input, adds 2 to it, and returns the result.
• +2 is the same, with syntactic sugar applied.
• if %3 ==0 then "multiple of 3" else "not a multiple of 3" ok denotes a function that takes a number and returns different strings depending on whether the number is divisible by 3.
• +2 *3 denotes a composition of two functions, which is, again, a function (one that takes a number, adds 2 to it, then multiplies the result by 3).

This chapter describes the different kinds of expressions in more detail.