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kandi X-RAY | rescript-lang.org Summary
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QUESTION
I'm trying to allow users to filter strings of text using a glob pattern whose only control character is *. Under the hood, I figured the easiest thing to filter the list strings would be to use Js.Re.test[https://rescript-lang.org/docs/manual/latest/api/js/re#test_], and it is (easy).
Ignoring the * on the user filter string for now, what I'm having difficulty with is escaping all the RegEx control characters. Specifically, I don't know how to replace the capture groups within the input text to create a new string.
So far, I've got this, but it's not quite right:
...ANSWER
Answered 2021-Jun-02 at 14:00Let me see if I have this right; you want to implement a character matcher where everything is literal except *. Presumably the * is supposed to work like that in Windows dir commands, matching zero or more characters.
Furthermore, you want to implement it by passing a user-entered character string directly to a Regexp match function after suitably sanitizing it to only deal with the *.
If I have this right, then it sounds like you need to do two things to get the string ready for js.re.test:
- Quote all the special regex characters, and
- Turn all instances of * into .* or maybe .*?
Let's keep this simple and process the string in two steps, each one using Js.re.replace. So the list of special characters in regex are [^$.|?*+(). Suitably quoting these for replace:
QUESTION
Is there a way to efficiently implement a group by function without mutation?
Naive implementation:
- ReScript playground
- JavaScript (see below)
ANSWER
Answered 2021-Jan-18 at 23:46You can group more simply by building an object of counts by date, and then using Object.entries and Array.map to convert that to an array of objects as required:
QUESTION
I would like to do the following. But it seems I cannot type the function parameter with one of the variant option. What would be the proper way to achieve this in rescript?
...ANSWER
Answered 2021-Apr-14 at 09:58Teacher and Student are not types themselves, but constructors that construct values of type person. If you want them to have distinct types you have to make it explicit:
QUESTION
I would like to make a validation function taking a name and outputting a validName type. I don't want to be able to construct values of type ValidName outside the module without using the function validateName.
I am trying to make the ValidName type private, but it makes it impossible for me to use it in the validateName function (event if it is in the same Module).
What is the right way to do this in rescript?
Here is the code:
...ANSWER
Answered 2021-Apr-01 at 19:14Visibility is specified in module signatures (as are type annotations, typically), not on the definitions themselves. You also don't need constructors, but should instead either make the type abstract, or the type alias private.
You can specify a module signature on a local module, as shown below, but typically you'd put it in a .resi ("interface") file. Everything you can put in a module signature you can also put in an interface file. See the docs for more.
This is how I would do it:
QUESTION
I am trying to simulate a side effect of writing to DB with rescript.
So I want to push the data in an array when calling repository.add. Js.Array.push returns an int, which I do not care about. I would like to force to return unit so that my signature shows unit which lets me know immediately that this function does a side effect.
Here is the code (and a playground here):
...ANSWER
Answered 2021-Mar-30 at 10:52A function will return unit if you return (), as you do. That isn't really the problem here. The reason the compiler complains is that you're implicitly ignoring the value returned by Js.Array.push, which is usually a mistake. You can shut the compiler up by explicitly ignoring it:
QUESTION
Given the following contrived example, is it possible to write a get function that can handle any record with an a property?
ANSWER
Answered 2021-Feb-16 at 08:39It's not. Because records are nominally (as opposed to structurally) typed, there is no way to specify "any record with an a field". Therefore get will be inferred to have the last type the compiler saw with an a field, which is type_two.
There is however the object type, which is structural with subtyping, allowing this:
QUESTION
After browsing through Rescript's API, it seems like there is no function that compares 2 strings that returns a boolean. The best option is localeCompare but it behaves somewhat different from the JS's ==. Why does localeCompare return a float instead of an integer?
ANSWER
Answered 2020-Dec-21 at 14:22You can compare strings using == in rescript as well. Alternatively there is a String.equal as well if you need a function restricted to strings specifically, The "native" (non-Js) standard library modules such as String unfortunately seems to be left out of the rescript documentation entirely.
localeComapre probably returns a float because it might be possible for it to return non-integer numbers. JavaScript unfortunately has no integer type, which makes it hard to know if it could return floats even if it seems obvious that it shouldn't. I've seen several of this kind of bugs myself in various bindings.
QUESTION
I'm writing a binding to let me write Service Workers in ReScript. String URLs and Requests are sometimes used interchangeably.
Where possible, I'm avoiding noise in the JS output.
What I know about [@bs.unwrap]I know I can write a binding for something like the add method using [@bs.unwrap] like so
ANSWER
Answered 2020-Nov-29 at 16:32You can use an abstract type and a set of conversion functions to "cast" values to that type, instead of the polymorphic variant:
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