Programming Research Group Technical Report TR-14-92

A certain loss of identity

Geraint Jones

1992, 9pp.

For pragmatic reasons it is useful to exclude the identity relation from the "implementable subset" of Ruby. However there are many expressions in the relational calculus whose natural meaning is just this identity relation. This note gives an identity-free account of some of these expressions, and shows that there is no satisfactory identity-free account of some others. This is an exercise in writing about Ruby without drawing any pictures, in part because it is about those expressions which would correspond to blank pictures.

This paper was presented at the Glasgow Functional Programming Group Workshop, Ayr, Scotland, 6 - 8 July 1992, and has also been published in Functional Programming, Glasgow 1992, eds. John Launchbury and Patrick Sansom, Springer Verlag, Workshops in Computing, 1992.

It is available as a 52,421 byte compressed PostScript file.