And Idris even enables a type-safe version: https://www.youtube.com/watch?v=fVBck2Zngjo

So if you mismatch the types you'll get a compile time error instead of a run time error.

That's pretty cool. Looking for the text version of it led me to another one more accessible to average programmer:

http://www.codeproject.com/Articles/159910/Extremely-Efficie...

F# also supports a typesafe printf format notation.

http://fsharpforfunandprofit.com/posts/printf/

To be clear, FORMAT is a function possibly with an associated compiler macro to expand constant format strings into more efficient code inline.