🚀 go-pugleaf

fs@caesar.cs.tulane.edu (Frank Silbermann) writes:

  >Because compromise between flexibility and safety
  >will always involve a trade-off, I believe that
  >untyped functional languages (e.g. those in the LISP/Scheme style)
  >will never become completely obsolete.

There is no meaningful expression which has no type. In the 
case of lists consisting of values of different type, functions 
must exist defined over all instances of the "untyped" list in a 
given program to give meaning to the list. Thus the values of the 
list must have some common property (a type). In the very rare case, 
this property is to be just an object; in most other cases, the 
property will be much more specific: e.g. to be a number,
a (graphic) view, etc.

  >Because such restrictions [on signatures] handcuff the programmer,
  >one line of reseach seeks to develop restrictions
  >for decidablilty which maximize polymorphism.

Yes. The pragmatic problem for the design of a strongly-typed language 
maximizing polymorphism (regarding to ML polymorphism) is that its 
much harder for a programmer to keep track of sophisticated decidability 
restrictions then of (in a way) "syntacticly" expressable restrictions 
like non-recursive signatures. And the type-checker must handle 
undecidable problems, e.g. must avoid its own non-termination, still 
giving comfortable error reports.


--
Wolfgang Grieskamp 
wg@opal.cs.tu-berlin.de tub!tubopal!wg wg%opal@DB0TUI11.BITNET