fp-ts is a library for typed functional programming in TypeScript.
Questions tagged [fp-ts]
198 questions
1
vote
1 answer
FP-TS: mapping responses
I am using the fp-ts library and I cannot figure out how to implement the following scenario:
Let's say I have a service with the request method getBooks(shelf, page) and the response looks like this (the request is paginated):
{
totalItems:…
Bibiana Sebestianova
- 11
- 3
1
vote
1 answer
Transform Either[] into Either
As the title says, I want to transform Either[] into Either
The rule is, if there is a single left-value (an error), I want to get a left-value with all the errors; otherwise, I want the right answers.
This seems like it should be…
Michael Lorton
- 43,060
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1
vote
1 answer
Find the smallest date in a list of dates using a Monod or a Semigroup
I was trying to build a function that folds and array of dates to the smallest date. I am using fp-ts for this, and I want to do it in a functional way.
I first tried to build it using Monoids, but there was not an easy way to build a min monoid…
Danielo515
- 5,996
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1
vote
2 answers
How to lookup the value for a key in type Json (fp-ts)?
I can extract a value from a json string in an Option with this code:
Code that works
import { identity, pipe } from "fp-ts/lib/function";
import * as E from "fp-ts/Either";
import * as O from "fp-ts/lib/Option";
import * as R from…
xav
- 4,101
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1
vote
1 answer
How to map a wrapped value in fp-ts?
I have this code and I was wondering if I can transform the below pipes into just one pipe?
const result: TE.TaskEither = pipe(
this.ensureFundsExist(),
TE.chain((funds) => {
return pipe(
…
Adam Arold
- 29,285
- 22
- 112
- 207
1
vote
1 answer
Simplify fp-ts function
I have this function:
export const getProducts = makeRequest(
/** Your query */
`asasd*[_type == "product"] {
_id,
title
}`,
/** Optionally transform the response */
(i) => i,
/** Validate exact type */
…
eivindml
- 2,197
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- 68
1
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2 answers
What problem does the Kleisli arrows solve in fp-ts?
I'm learning functional programming by using fp-ts lib and noticed that some functions end with K, like:
chainTaskEitherK
chainEitherK
fromTaskK
Also I read the explanation of What a K suffix means in fp-ts documentation, but unfortunately I can't…
Roman Mahotskyi
- 4,576
- 5
- 35
- 68
1
vote
1 answer
How to build a correct data flow using Do-notation?
I just started to learn functional programming world by using fp-ts lib. At this moment I can understand basic concept of proposed function by this lib, but I can't understand how to glue them all together in the single data flow.
I would like to…
Roman Mahotskyi
- 4,576
- 5
- 35
- 68
1
vote
4 answers
How to handle "else if" in fp-ts
A lot of times I notice I am struggling how to implement a pretty simple flow chart with multiple if-else conditions.
This example looks too verbose and is not really scalable if more conditions are added later on:
import * as O from…
Mr.B
- 67
- 3
- 9
1
vote
1 answer
How to perform grouped-by aggregations on array of objects in fp-ts?
I'm trying to analyze data given as an array of nested objects. I want to use fp-ts ecosystem, and I'm trying to figure out how I could combine a grouped-by calculation with any pre-defined function (such as, calculating average, median, mode, sum,…
Emman
- 3,695
- 2
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- 44
1
vote
1 answer
Cannot fix error Types of parameters 'r' and 'a' are incompatible
I try to replicate this code from this blog, but running into some pretty obscure errors
import { option, identity, apply } from 'fp-ts';
import type { Kind, URIS } from 'fp-ts/HKT';
import { pipe } from 'fp-ts/lib/function';
type OrderId =…
Sté
- 195
- 11
1
vote
1 answer
Does fp-ts have loop functionality
Does fp-ts have any functionality to do a while loop (stack safe) with timeout. Like tail recursion, Y Combinator or something. I have seen ChainRec, but there aren't really any documentation besides functions signatures.
Exact issue I have:
I need…
Danil
- 103
- 7
1
vote
0 answers
dynamic Optional.fromPath
Can i access nested properties with monocle-ts in a dynamic fashion?
The closest i can find directly from the library is the Optional.fromPath, combined with a dynamic path. Based on the example from the documentation for fromPath we can create a…
Simon
- 621
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- 21
1
vote
1 answer
How do I convert this to a Point-free function
import { chain, map, Apply } from "fp-ts/lib/IO";
import { log } from "fp-ts/lib/Console";
import { pipe } from "fp-ts/lib/function";
import * as D from "fp-ts/lib/Date";
import { sequenceT } from "fp-ts/lib/Apply";
import { v4 as uuidv4 } from…
Nikos Kalogridis
- 25
- 1
- 5
1
vote
3 answers
Ramda pick for fp-ts options / maybe
Using fp-ts. I have an option of an array
const arrayofKeys: Option>,
and an option of a record
const record: Option>
I want to pick the Vs of the Record where Ks intersect with the Array and stick the result in an Option.
In…
Simon
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