Version française
Home     About     Download     Resources     Contact us    
Browse thread
[Caml-list] semi-colons and begin
[ Home ] [ Index: by date | by threads ]
[ Search: ]

[ Message by date: previous | next ] [ Message in thread: previous | next ] [ Thread: previous | next ]
Date: -- (:)
From: Chris Hecker <checker@d...>
Subject: [Caml-list] semi-colons and begin

I must admit I'm still slightly confused about the semicolon thing, even after writing a fair amount of caml code.  The current sticking point is that 

# if false then print_int 2; print_int 3;;
3- : unit = ()

# if false then print_int 2; print_int 3 else ();;
Characters 39-43:
Syntax error
# 

# if false then begin print_int 2; print_int 3 end;;
- : unit = ()
# if false then begin print_int 2; print_int 3 end else ();;
- : unit = ()

The "BNF" grammar implies the first and second tests should compile and print nothing, since expr = expr ; expr, although Xavier et al. have said the BNF in the docs isn't really accurate.

I also thought begin...end was needed in a pattern-match, but apparently expr ; expr works there?

Is there a chart or something that says exactly where they're allowed?  I'm afraid of introducing a subtle bug in my program.  In C I always use brackets with my if statements to avoid the similar problem, so I suppose I could use begin..end everywhere, but yuck!

Chris

-------------------
To unsubscribe, mail caml-list-request@inria.fr.  Archives: http://caml.inria.fr