úÎ  “ =Thrown when attempting to evaluate a placeholder at runtime. @Indicates that this piece of code has not yet been implemented.  $notImplemented = $(placeholder "Unimplemented feature")CIndicates unimplemented code or a known bug with a custom message. $(todo msg) = $(placeholder ("TODO: " ++ msg))GGenerates an expression of any type that, if evaluated at runtime will  throw a . It is therefore similar to  , except H that the source location is automatically included. Also, a warning is % generated at compile time so you won'!t forget to replace placeholders  before packaging your code.  Similar to 0, but does not generate a compiler warning. Use  with care!       placeholders-0.1Development.PlaceholdersPlaceholderExceptionnotImplementedtodo placeholderplaceholderNoWarningbaseGHC.Errerror emitWarning formatMessage formatLoc