Type checker user interface and error reporting

[nha...@gmail.com]

Displaying helpful type errors with Shen's type system seems quite difficult due to the way the system works. I wonder how useful in practice it would be to generate a heat map colorized with the number of times a particular sub-expression failed to unify during type checking and have it fed back into the IDE. This may also indirectly help show which type rules cause excessive backtracking.

[Mark Tarver]

Type checking in Shen is nondeterministic and the problems of modelling the computation for humans is akin to the problem of creating a good Prolog trace 

package.  The heatmap idea is good; you can try

(datatype heatmap

  let Heatmap (heatmap P)

  if false;

  _________________________

  P;)

(define heatmap

   P -> (set *heatmap* [P | (value *heatmap*)]))

as a catch-all default rule and see what you catch.

Mark