141 lines
3.4 KiB
Markdown
141 lines
3.4 KiB
Markdown
# Inato `fp-ts` training
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This repo is a work in progress toward having a comprehensive training material
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to onboard people on using `fp-ts` efficiently.
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The exercices consist of unimplemented functions and their associated failing
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tests.
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To run the tests, simply run
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```sh
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$ yarn test
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```
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You can also run them in watch mode:
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```sh
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$ yarn test:watch
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```
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Finally, if you wish to only run the tests for a given exercice `exoN`, you can
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run the following:
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```sh
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$ yarn test[:watch] exoN
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```
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The exercices are organized into `exoN` folders and most of what is required to
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complete each is detailed in the comments.
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## code style guide
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For readability purpose, we replace `ReaderTaskEither` by `rte`
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- Use `flow` instead of `pipe` when possible
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> Why? Using flow reduces the amount of variables to declare in a method, hence the visibility and readability of the code
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```typescript
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// Bad
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const formatUserPhoneNumber = (user: User) =>
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pipe(user, User.phoneNumber, User.formatPhoneNumber);
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// Good
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const formatUserPhoneNumber = flow(User.phoneNumber, User.formatPhoneNumber);
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```
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- Avoid using `boolean` method `match` when unecessary
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> Why? boolean.match can lower the global understanding of a method and enforce nested pipes. Using classic `if/else` is often the best option
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```typescript
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// Bad
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const triggerEmailCampaign = ({
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user,
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...emailSettings
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}: {
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user: User} & EmailSettings) =>
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pipe(
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user.nationality === 'FR',
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boolean.match(
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() => triggerGlobalEmailCampain({ to: user.email, emailSettings }),
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() => triggerFrenchEmailCampaign({ to: user.email, emailSettings }),
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),
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);
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// Good
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const triggerEmailCampaign = ({
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user,
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...emailSettings
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}: { user: User } & EmailSettings) => {
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if (user.nationality === 'FR') {
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return triggerFrenchEmailCampaign({ to: user.email, emailSettings });
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}
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return triggerGlobalEmailCampain({ to: user.email, emailSettings });
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```
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- Avoid nested pipes
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> Why? They lower global understanding of the code. We allow ourselves 2 levels of piping maximum per function and tend to do atomic functions instead
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```typescript
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// Bad
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const convertDollarAmountInCountryCurrency = ({
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countryName,
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amountInDollar,
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}: {
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countryName: CountryName;
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amountInDollar: number;
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}) =>
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pipe(
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getCountryCode(countryName),
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either.map(
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countryCode =>
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pipe(
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getCountryCurrency(countryCode),
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option.map(currency =>
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pipe(
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amountInDollar,
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converFromDollar(currency),
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convertedAmount =>
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console.log(
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`converted amount for country ${countryCode} is ${convertedAmount}`,
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),
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),
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),
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),
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),
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),
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);
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// Good
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const convertDollarAmountInCountryCodeCurrency = ({
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amountInDollar,
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countryCode,
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}: {
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amountInDollar: number;
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countryCode: CountryCode;
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}) =>
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pipe(
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getCurrencyFromCountryCode(countryCode),
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option.map(currency => {
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const convertedDollarAmount = convertFromDollar(currency)(currency);
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console.log(
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`converted amount for country ${countryCode} is ${convertedAmount}`,
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);
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}),
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);
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const convertDollarAmountInCountryCurrency = ({
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amountInDollar,
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countryName,
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}: {
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amountInDollar: number;
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countryName: CountryName;
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}) =>
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pipe(
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getCountryCode(countryName),
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either.map(countryCode =>
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convertDollarAmountToCountryCodeCurrency({ amountInDollar, countryCode }),
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),
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);
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```
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