Frantisek Farka
Hello cafe,
I was looking into Haskell Report 2010 and notice something in the definition of case statement:
https://www.haskell.org/onlinereport/haskell2010/haskellch3.html#x8-460003.1...
Apparently an empty alternative within case statement is a plausible production. ('alt' production rule, third option).
If I get it correctly, following example shows the empty alternative:
cStmt e = case e of { 'a' -> True ; {-- empty here --} ; 'b' -> False }
What I miss is any ratio behind this. What is the empty alternative good for? Any idea?
Looks like it's to allow "case e of {}". Notice that "lexp" requires an "alts" and "alts" requires at least 1 "alt", so for empty braces to be acceptable there must be an empty alt for them to 'contain'. Cheers, Chris