State the intent of Invalid_argument, Failure, and Sys_error
State the intent of Invalid_argument, Failure, and Sys_error

(Christophe Troestler)

This stems from the discussion https://github.com/ocaml/ocaml/pull/250
where the importance (or not) of pattern matching on the string
literal was raised.

git-svn-id: e40234e4c881bffaae8eee4067ddafaf89232d37@16449 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02

gerdstolpmann/ocaml,eliberis/ocaml,eliberis/ocaml,eliberis/ocaml,yunxing/ocaml,yunxing/ocaml,msprotz/ocaml,msprotz/ocaml,gerdstolpmann/ocaml,msprotz/ocaml,eliberis/ocaml,yunxing/ocaml,yunxing/ocaml,eliberis/ocaml,gerdstolpmann/ocaml,msprotz/ocaml,gerdstolpmann/ocaml,gerdstolpmann/ocaml,yunxing/ocaml,msprotz/ocaml