nicolashery

Using MonadLogger without LoggingT in Haskell

nicolashery

Using RIO with Servant in Haskell, with nested environments.

Port of servant-nested-apis Gist.

nicolashery

Nesting APIs and ReaderT environments in Haskell's Servant

Environments, from parent to child (or base to extended):

• App (ReaderT AppEnv IO):
  • HasLogFunc env
  • HasDatabase env
  • HasTracing env
• AppAuthenticated (ReaderT AppAuthenticatedEnv IO):
• HasApp env (everything from App)

nicolashery

Compare using a stack of transformers vs. the ReaderT pattern for a web service.

See files:

• Transformers.hs
• Reader.hs

nicolashery

App-wide vs. Handler-specific environments in Haskell's Servant

See files:

• Bad.hs
• Good.hs

Client requests:

nicolashery

module AsyncMonadBaseControlExample where

import Blammo.Logging (LoggingT)
import Control.Concurrent.Async.Lifted.Safe (concurrently)
import Control.Monad.Base (MonadBase)
import Control.Monad.Reader (MonadIO, MonadReader, MonadTrans (lift), ReaderT)
import Control.Monad.Trans.Control (MonadBaseControl (liftBaseWith, restoreM), StM)
import Data.Text.Lazy qualified as TL
import Web.Scotty.Trans (ActionT, text)

nicolashery

#!/usr/bin/env stack
{- stack
  --resolver lts-13.4
  --install-ghc
  script
  --ghc-options "-Wall"
  --package aeson
  --package aeson-pretty
  --package aeson-typescript
  --package base

nicolashery

Emulating "enums" in JSDoc version of TypeScript

Problem

TypeScript has support for type-checking plain JavaScript files, which is very useful if you have an existing JS codebase and you want to test the waters and gradually add types.

There are some limitations in what you can do in JSDoc, but a lot of them can be worked-around by using type-definition files .d.ts (for example in a types/ directory). These files don't generate any JavaScript code, they are just there to provide extra type definitions to the compiler.

One thing you can't do in those .d.ts files though, is use enums. You could define them of course, but you won't get the runtime representation since the files don't generate JS code.

nicolashery

CLOSURE_COMPILER_VERSION := 20180101
CLOSURE_COMPILER_URL := http://dl.google.com/closure-compiler/compiler-$(CLOSURE_COMPILER_VERSION).tar.gz

closure-compiler:
  mkdir -p vendor
	curl -o vendor/closure-compiler.tar.gz $(CLOSURE_COMPILER_URL)
	tar -C vendor/ -zxf vendor/closure-compiler.tar.gz
	mv vendor/closure-compiler-v$(CLOSURE_COMPILER_VERSION).jar vendor/closure-compiler.jar
	rm vendor/COPYING vendor/README.md vendor/closure-compiler.tar.gz
  

nicolashery

node_modules
dist