Re:Functors, applicatives, and monads in pictures
by chongli on Wednesday May 29, 2013 @05:32AM
(#5785400)
Yeah, you're talking about the mathematical definition of a bound variable. Functional programming languages use this whenever you define a function:
foo x = x * 2
Every time you call foo, x is bound to a new value (but only within the scope of foo). This is not the same as mutating some memory location associated with the name x.
For example, if you integrate x^2 dx from x=0 to 10, x changes continuously.
It's clear that x is not fixed to any particular value.