[danidiaz]

> Define true as a lambda taking two lazy values that returns the first, and false as one that returns the second, and you can turn all booleans into lambdas with no increase in code clarity.

This is trivially true, any datatype can be encoded as a function. The post is not saying that we can pass any type of lambda whatsoever, but that we should pass lambdas that implement the required functionality.

> The straw man in the post - talking about a case-sensitive matcher that selectively called one of two different functions based on a boolean - is indeed trivially converted into calling a single function passed as an argument, but it's hard to say that it's an improvement. Now the knowledge of how the comparison is done is inlined at every call point

If call sites shouldn't choose wich lambda (or boolean) to pass, simply define a new function that always passes the same lambda to the original function, and use it everywhere. (This could also be a good case for partial application.)

[eru]

> This is trivially true, any datatype can be encoded as a function.

To elaborate: this is called the church encoding of the data type. Particularly interesting for recursive data types.

The most common example is probably 'foldr' (or 'reduce' in Lisp-parlance) for linked lists.