Hello Volker, All identifiers prefixed with an underscore are "typed holes", see: https://downloads.haskell.org/~ghc/7.8.3/docs/html/users_guide/typed-holes.html
Edward Excerpts from Volker Wysk's message of 2015-01-20 10:36:09 -0800: > Hello! > > What is a "hole"? > > This program fails to compile: > > main = _exit 0 > > I get this error message: > > ex.hs:1:8: > Found hole ‘_exit’ with type: t > Where: ‘t’ is a rigid type variable bound by > the inferred type of main :: t at ex.hs:1:1 > Relevant bindings include main :: t (bound at ex.hs:1:1) > In the expression: _exit > In an equation for ‘main’: main = _exit > > When I replace "_exit" with "foo", it produces a "not in scope" error, as > expected. What is special about "_exit"? It doesn't occur in the Haskell > Hierarchical Libraries. > > Bye > Volker > _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
