redis.hs

{-# LANGUAGE OverloadedStrings #-}

import Database.Redis hiding (decode)
import Text.JSON
import Data.ByteString.Char8 (unpack)
import Control.Arrow (left)
import Data.Traversable (traverse)

getValueFromJSON json = decode json >>= valFromObj "value" :: Result (Float)

getEvents = do
  result <- zrange "test-range" 0 4
  return $ do
    items <- left show result
    (resultToEither . traverse (getValueFromJSON . unpack)) items

main = do
  conn <- connect defaultConnectInfo
  runRedis conn getEvents

redis.rb

require "json"
require "redis"

redis = Redis.new
puts redis.zrange("test-range", 0, 4).map {|e| JSON.parse(e)["value"].to_f }.inspect

results.txt

 ~cur_dir λ ./test.sh                                                                                                                                                                                                               20:14:45


1. No key
= Haskell =
Right []
= Ruby =
[]


2. Valid JSON
= Haskell =
Right [123.0]
= Ruby =
[123.0]


3. Missing JSON field
= Haskell =
Left "valFromObj: Could not find key: \"value\""
= Ruby =
[0.0]


4. Invalid JSON
= Haskell =
Left "Invalid tokens at end of JSON string: \" 123\""
= Ruby =
/Users/teamon/.rbenv/versions/1.9.3-p194/lib/ruby/1.9.1/json/common.rb:148:in `parse': 743: unexpected token at '"val" 123' (JSON::ParserError)
  from /Users/teamon/.rbenv/versions/1.9.3-p194/lib/ruby/1.9.1/json/common.rb:148:in `parse'
	from redis.rb:5:in `block in <main>'
	from redis.rb:5:in `map'
	from redis.rb:5:in `<main>'


5. Invalid value
= Haskell =
Left "Unable to read Float"
= Ruby =
[0.0]


6. No redis
= Haskell =
redis.hs: connect: does not exist (Connection refused)
= Ruby =
/Users/teamon/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/redis-3.0.2/lib/redis/client.rb:268:in `rescue in establish_connection': Error connecting to Redis on 127.0.0.1:6379 (ECONNREFUSED) (Redis::CannotConnectError)
	from /Users/teamon/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/redis-3.0.2/lib/redis/client.rb:263:in `establish_connection'
	from /Users/teamon/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/redis-3.0.2/lib/redis/client.rb:69:in `connect'
	from /Users/teamon/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/redis-3.0.2/lib/redis/client.rb:282:in `ensure_connected'
	from /Users/teamon/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/redis-3.0.2/lib/redis/client.rb:173:in `block in process'
	from /Users/teamon/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/redis-3.0.2/lib/redis/client.rb:248:in `logging'
	from /Users/teamon/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/redis-3.0.2/lib/redis/client.rb:172:in `process'
	from /Users/teamon/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/redis-3.0.2/lib/redis/client.rb:84:in `call'
	from /Users/teamon/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/redis-3.0.2/lib/redis.rb:1396:in `block in zrange'
	from /Users/teamon/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/redis-3.0.2/lib/redis.rb:36:in `block in synchronize'
	from /Users/teamon/.rbenv/versions/1.9.3-p194/lib/ruby/1.9.1/monitor.rb:211:in `mon_synchronize'
	from /Users/teamon/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/redis-3.0.2/lib/redis.rb:36:in `synchronize'
	from /Users/teamon/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/redis-3.0.2/lib/redis.rb:1395:in `zrange'
	from redis.rb:5:in `<main>'

table.md

Test	Haskell	Ruby
No key	OK	OK
Valid JSON	OK	OK
Missing JSON field	OK	Silent fail
Invalid JSON	OK	Exception
Invalid value	OK	Silent fail
No redis	Error	Exception

test.sh

#!/usr/bin/env bash

function go {
  echo "= Haskell ="
  runhaskell redis.hs
  echo "= Ruby ="
  ruby redis.rb
}

function hd {
  echo
  echo
  echo $1
}


hd "1. No key"
redis-cli DEL "test-range" > /dev/null
go

hd "2. Valid JSON"
redis-cli DEL "test-range" > /dev/null
redis-cli ZADD "test-range" 10.0 '{"value": 123}' > /dev/null
go

hd "3. Missing JSON field"
redis-cli DEL "test-range" > /dev/null
redis-cli ZADD "test-range" 10.0 '{"val": 123}' > /dev/null
go

hd "4. Invalid JSON"
redis-cli DEL "test-range" > /dev/null
redis-cli ZADD "test-range" 10.0 '"val" 123' > /dev/null
go

hd "5. Invalid value"
redis-cli DEL "test-range" > /dev/null
redis-cli ZADD "test-range" 10.0 '{"value": "blah"}' > /dev/null
go


hd "6. No redis"
launchctl unload -w ~/Library/LaunchAgents/homebrew.mxcl.redis.plist
go
launchctl load -w ~/Library/LaunchAgents/homebrew.mxcl.redis.plist