pattern-matching

Has anyone got experience with developing an application to replace the default lock screen? I've been told it is not possible, however this application manages it. Any tutorials or guidance you know of would be appreciated. KBusc 100% possible. Here are some links to get you started. Android App and Pattern Lock Screen Android Lock Screen Widget Developing a custom lock screen Try this one: lockscreenswitchwidget You can implement deviceAdminReciever to use device locks and all please have a look at this it explains everything about locks setting passwords..... Update: Use this library Link

I'm trying to find a way to match a query to a regular expression in a database. As far as I can tell (although I'm no expert), while most DBMS like MySQL have a regex option for searching, you can only do something like: Find all rows in Column 1 that match the regex in my query. What I want to be able to do is the opposite, i.e.: Find all rows in Column 1 such that the regex in Column 1 matches my query. Simple example - say I had a database structured like so: +----------+-----------+ | Column 1 | Column 2 | +----------+-----------+ | [a-z]+ | whatever | +----------+-----------+ | [\w]+ |

Say I have two use cases for a function. Do something with users that have a subscription and something with users that don't have a subscriptions. def add_subscription(subscription_id, %User{subscription: nil}) # Do something with user here. And def add_subscription(subscription_id, user) How do I do pattern matching like this and also still use the user in the first function? Thanks! You can bind the function argument to a variable: def add_subscription(subscription_id, %User{subscription: nil} = user) The convention is to assign after the pattern match: # Do This def foo(%User{subscription:

How to do pattern matching on a Map in Scala ? A (non working) attempt includes, Map("a"->1, "b"->2, "c"->3) match { case Map(a,b,_*) => a } which errs with value Map is not a case class, nor does it have an unapply/unapplySeq member case Map(a,b,_*) => a The error is indicative enough, yet how to enrich Map with an unapply method for pattern matching ? Many Thanks Update Following @Paul's comment, a neater use case may be like this, Map("a"->1, "b"->2, "c"->3) match { case Map("b"->2,_*) => "222" } namely, in this case, if map contains key b that maps onto value 2 . Most easy way is tramsform

In Scala, I have a regular expression pattern match like this: val Regex = """(\d{4})/(\d{2})/(\d{2})""".r val Regex(year, month, day) = "2013/01/06" The result is: year: String = 2013 month: String = 01 day: String = 06 How can I accomplish a similar result in Haskell? In other words, can I match a regular expression containing groups and assign the groups to identifiers? This works for me: Prelude Text.Regex.Posix> "2013/01/06" =~ "([0-9]+)/([0-9]*)/([0-9]*)" :: (String,String,String,[String]) ("","2013/01/06","",["2013","01","06"]) (ghci 7.4.2 on OS X) Ralph Expanding on Chris's answer ,

Why can OCaml generate efficient machine code for pattern matching and not for if-else tests? I was reading Real World OCaml and I came across this section where they compared the performance of pattern matching to the performance of if-else tests. It turned out that pattern matching in their example was significantly faster than if-else tests. Even though the code doesn't utilize any special pattern match cases that would not be possible with if-else tests, it just compares integers. They ascribe compiler optimization for pattern matching as the reason for the performance difference. The