Zero

This page talks about how implementations handle various aspects of zero. Thanks to Alexey Radul for the ideas here; the research is mine.

Exact division by zero

Racket, MIT, Gambit, Chicken, Bigloo, Scheme48/scsh, Chibi, Guile, SISC, Chez, Ikarus/Vicare, Larceny, Ypsilon, Mosh, IronScheme, NexJ, STklos, Shoe, Scheme 7, BDC, XLisp, Rep, Schemik, Elk, UMB, SigScheme, SXM, Sizzle, Spark, Dfsch, Inlab, VSCM report an error.

Gauche, SCM, KSi, VX return inexact infinity.

Kawa returns exact infinity.

Scheme 9, Femtolisp return an incorrect result.

Inexact division by exact zero

Racket, Gambit, Chicken, scsh, Chibi, Guile, Shoe, Scheme 7, BDC, XLisp, Rep, Schemik, Elk, SXM, Sizzle, Spark, Dfsch, Inlab, VSCM report an error.

Gauche, Bigloo, Scheme48, Kawa, SISC, SCM, Chez, Ikarus/Vicare, Larceny, Ypsilon, Mosh, IronScheme, NexJ, STklos, UMB, VX return inexact infinity.

MIT reports an error unless floating traps are ignored, in which case it returns inexact infinity.

SigScheme, Dream, Oaklisp, Owl Lisp do not support inexact numbers.

KSi, Scheme 9, Femtolisp return an incorrect result.

Division by inexact zero

Plain Chicken, scsh, Shoe, TinyScheme, XLisp, Rep, Schemik, Scheme 7, SXM, Sizzle, Dfsch, Inlab, VSCM report an error.

Racket, Gauche, MIT, Gambit, Chicken with the numbers egg, Bigloo, Scheme48, Guile, Kawa, SISC, Chibi, SCM, Chez, SCM, Ikarus/Vicare, Larceny, Ypsilon, Mosh, IronScheme, NexJ, STklos, BDC, Elk, UMB, VX, Spark, Femtolisp return inexact infinity.

SigScheme, Dream, Oaklisp, Owl Lisp do not support inexact numbers.

KSi, Scheme 9 return an incorrect result.

Inexact multiplication by exact zero

Racket, MIT, Gambit, Chez, Ypsilon, TinyScheme, XLisp, Elk, SXM, Sizzle, Spark, Inlab return exact 0.

Gauche, Chicken, Bigloo, Scheme48/scsh, Guile, Kawa, SISC, Chibi, SCM, Ikarus/Vicare, Larceny, Mosh, IronScheme, NexJ, STklos, KSi, Shoe, Scheme 9, Scheme 7, BDC, Rep, Schemik, UMB, VX, Femtolisp, Dfsch, VSCM return inexact 0.0.

SigScheme, Dream, Oaklisp, Owl Lisp do not support inexact numbers.

Complex numbers with 0.0 imaginary part.

Gauche, MIT, Chicken with the numbers egg, Scheme48/scsh, Kawa, SISC, SCM, STklos, KSi, Scheme 7, UMB, Spark, Dfsch, VSCM consider 3.0+0.0i to be a real number.

Racket, Gambit, Guile, Chibi, Chez, Vicare, Larceny, Ypsilon, Mosh, IronScheme do not.

Bigloo, Ikarus, NexJ, SigScheme, Shoe, TinyScheme, Dream, Scheme 9, BDC, XLisp, Rep, Schemik, Elk, VX, Oaklisp, SXM, Sizzle, Femtolisp, Inlab, Owl Lisp do not implement non-real numbers.

Negative zero =

Racket, Gambit, Guile, Chez, Vicare, Spark, Femtolisp distinguish between 0.0 and -0.0.