A recent posting that expressed a desire for #ifdef struck me as perverse. A prime reason for using Haskell is its elegance and clarity. To adopt the most inelegant and turgid feature from C would be like encouraging graffiti in a museum. Most #ifdef's and #if's memorialize failures of imagination or care, often in the name of "portability". Code is NOT portable if it has to be rewritten according to the conventions of each environment. Ifdef expresses just such rewriting, and in an egregious style: it inverts the logical structure of a program, bringing the tweaks to the top while fragmenting the real architecture. To make code portable, one should first get rid of system dependencies to the greatest extent possible. Then treat the recalcitrant residue with the same sense of style as any other programming task. Some standard methods that apply everywhere in programming are equally helpful for portability: Modularization (sweeping systemisms into a corner) Generalization (rising above the systemisms) For dealing with the recalcitrant residue, a method that Haskellites should find specially sympathetic is Specialization (freezing certain parameter values) Ifdef, if course, is a specialization technique, but from another era. If there really is a need for specialization, it would be far better to employ a Ershovian specializer that creates Haskell from Haskell rather than from stone-age idioms. Is one available? Doug McIlroy