Add SwitchStore and CaseLet (#594)

* wip

* ttt

* simplfiy

* wip

* wip

* wip

* wip

* wip

* wip

* wip

* wip

* fix

* wip

* wip

* wip

* wip

* wip

* wip

* wip

* wip

* wip

* docs

* wip

* wip

* wip

* wip

* wip

* updates

* revert ttt stuff'

* xcode 11 fixes

Co-authored-by: Stephen Celis <[email protected]>

Author: mluisbrown

Sources/ComposableArchitecture/Internal/Breakpoint.swift

@@ -2,7 +2,7 @@
   import Darwin
 #endif
 /// Raises a debug breakpoint iff a debugger is attached.
-@inline(__always) func breakpoint() {
+@inline(__always) func breakpoint(_ message: @autoclosure () -> String = "") {
   #if DEBUG && canImport(Darwin)
     // https://github.com/bitstadium/HockeySDK-iOS/blob/c6e8d1e940299bec0c0585b1f7b86baf3b17fc82/Classes/BITHockeyHelper.m#L346-L370
     var name: [Int32] = [CTL_KERN, KERN_PROC, KERN_PROC_PID, getpid()]
@@ -20,6 +20,8 @@
     if isDebuggerAttached {
       fputs(
         """
+        \(message())
+
         Caught debug breakpoint. Type "continue" ("c") to resume execution.
 
         """,