Determine parameters in advance

Bind Bind parameter

We know that you can use bind to pre-bind parameters

But that would add a nasty null.

You can remove this null with Curry:

You can also use partial:

Bind/curry/partial can bind parameters, but only the front parameters. What if I want to bind parameters in the middle or behind?

See the examples:

You can see that each time readFile is followed by ‘utf8’ and output.

So you might rewrite it like this:

It looks good.

Placeholders are used to solve this problem, but only if the function is Curryized:

Then optimize it a little bit:

You can assume that the position of __ is where file1. TXT and file2. TXT appear.

Is that intuitive?

That’s how placeholders are used.

Reference: hackernoon.com/i-ramda-par…