Testing the usual suite of Schemes to see whether promises returned by delay are disjoint from procedures.
Disjoint: Racket, Gauche, MIT, Gambit, Chicken, Guile, Kawa, Chibi, SCM, STklos, SigScheme, TinyScheme, XLisp, Elk, UMB, VX, SXM, Sizzle, Spark
Not disjoint: Bigloo, Scheme48/scsh, SISC, Chez, Vicare, Larceny, Ypsilon, Mosh, IronScheme, NexJ, Scheme 9, Schemik, Inlab, Owl Lisp
delay undefined: KSi, Shoe, Scheme 7, Rep, Llava, FemtoLisp, Dfsch
Buggy implementation: Oaklisp