js: partial application example

pa.js

calculate = function(a, f) { return a.reduce(function(x,y) { return f(x, y) }); }

sum = function(a, b) { return a + b; }
sub = function(a, b) { return a - b; }

sumAll = function(a) { return calculate(a, sum); }
subAll = function(a) { return calculate(a, sub); }