Errata

In the first example using the curry3 function, it reads:
var songsPlayed = curry3(_.uniq)(false)(songToString);

It should be:
var songsPlayed = curry3(_.uniq)(songToString)(false);

Both versions work because _.uniq would shift the parameters when the second parameter is not boolean, but the idea of the text was about letting curry3 take the last (third) parameter in the first function call, which should be 'songToString'.

In Figure 1-10, the left side shows predicates named isPrime, isOdd and isEven. These predicates act on a single value and do not compare one value to another, so it doesn't make sense to use them with the comparator function.

At the top of the page in the functions below the "second" should be _.second and the "nth(row, 2)" should be "_.nth(row, 2)" Both of these are underscore functions that are not written as such and are therefore very confusing.


function selectAges(table) {
return _.rest(_.map(table, second));
}
function selectHairColor(table) {
return _.rest(_.map(table, function(row) {
return nth(row, 2);
}));
}

// 'array[i]' should be 'elem' or,
// 'i' should be the second parameter to anonymous function.
_.each(array, function(elem) {
doSomething(array[i]);
}

I think the cat function should verify that head is an array so it knows it can call concat on it.

if (existy(head) && _.isArray(head))

In footnote 6 about apply it says "I use null to signal that this should just refer to the global object". That's not correct. Passing null signals that this should refer to null. If inside the function a call is made to this.foo(), it won't try to call foo as a method on the global object. There will be an error.

It is implied that these lines are equivalent, but they are not.

return _.isFunction(doSomething) ? doSomething() : doSomething;

return action();

The first line only calls doSomething if it is a function.
The second line assumes action is a function.

The comparator function on page 14 won't work as intended if the predicate function passed to it returns the true for both less than and equal to. In that case the comparator function will never return zero. The predicate function passed to comparator on page 15 should be "less", not "lessOrEqual". The easiest fix would be to change "lessOrEqual" to "less" throughout the examples in this section and of course use < instead of <=.