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April 6, 2022 10:00
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| #!/usr/bin/env nix-shell | |
| #! nix-shell -p "ghc.withPackages (pkgs: with pkgs; [ mtl transformers lens ]) " ghcid | |
| #! nix-shell -I nixpkgs=https://github.com/nixos/nixpkgs-channels/archive/nixos-unstable.tar.gz | |
| -- #! nix-shell -i "ghcid -c 'ghci -Wall' -T main" | |
| #! nix-shell -i runghc | |
| {-# LANGUAGE ViewPatterns #-} | |
| {-# LANGUAGE LambdaCase #-} | |
| {-# LANGUAGE BangPatterns #-} | |
| {-# LANGUAGE FlexibleContexts #-} | |
| {-# LANGUAGE OverloadedStrings #-} | |
| {-# LANGUAGE ScopedTypeVariables #-} | |
| -- case claState of | |
| -- Nothing -> pure [] | |
| -- Just cla -> do | |
| -- claStatus <- getClaStatusObject lrId | |
| -- case claStatus of | |
| -- Nothing -> pure [cla] | |
| -- Just claStatus' -> do | |
| -- generateOffer <- getGenerateOfferObject lrId | |
| -- case generateOffer of | |
| -- Nothing -> pure ([cla] <> [claStatus']) | |
| -- Just genOff -> do | |
| -- fetchOffer <- getfetchOfferStatusObject lrId | |
| -- case fetchOffer of | |
| -- Nothing -> pure ([cla] <> [claStatus'] <> [genOff]) | |
| -- Just fetchOff -> pure ([cla] <> [claStatus'] <> [genOff] <> [fetchOff]) | |
| module Main where | |
| import Control.Monad.Trans.Writer.Strict | |
| import Control.Monad.Trans.Maybe | |
| import Control.Monad.IO.Class | |
| import Control.Monad.Trans.Class | |
| getClaStatusObject :: MonadIO m => a -> m (Maybe Int) | |
| getClaStatusObject _ = liftIO $ pure (Just 1) | |
| getGenerateOfferObject :: MonadIO m => a -> m (Maybe Int) | |
| getGenerateOfferObject _ =liftIO $ pure (Just 2) | |
| getfetchOfferStatusObject :: MonadIO m => a -> m (Maybe Int) | |
| getfetchOfferStatusObject _ =liftIO $ pure (Just 3) | |
| main :: IO () | |
| main = do | |
| xs <- execWriterT $ runMaybeT $ snippet | |
| print xs | |
| snippet :: MaybeT (WriterT [Int] IO) () | |
| snippet = | |
| do | |
| let | |
| lrId = undefined | |
| cla <- MaybeT $ getClaStatusObject lrId | |
| lift $ tell [cla] | |
| generateOffer <- MaybeT $ getGenerateOfferObject lrId | |
| lift $ tell [generateOffer] | |
| fetchOffer <- MaybeT $ getfetchOfferStatusObject lrId | |
| lift $ tell [fetchOffer] |
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