Add loops and document optionnal else in conditional

Syntax:
foreach id from exp (to|downto) exp (by exp)? exp

foreach and by are keywords; from, to and downto aren't.

1 files changed, 7 insertions, 0 deletions

diff --git a/language/l2_parse.ott b/language/l2_parse.ott
index 4e965d7c..99465f65 100644
--- a/language/l2_parse.ott
+++ b/language/l2_parse.ott
@@ -613,6 +613,13 @@ exp :: 'E_' ::=
   | if exp1 then exp2 else exp3                         :: :: if
     {{ com conditional }}
 
+  | if exp1 then exp2                                   :: S :: ifnoelse {{ icho [[ if exp1 then exp2 else unit ]] }}
+
+  | foreach id from exp1 to exp2 by exp3 exp4           ::   :: for {{ com loop }}
+  | foreach id from exp1 to exp2 exp3                   :: S :: forbyone  {{ icho [[ foreach id from exp1 to exp2 by 1 exp4 ]] }}
+  | foreach id from exp1 downto exp2 by exp3 exp4       :: S :: fordown {{ icho [[ foreach id from exp1 to exp2 by ( - exp3 ) exp4 ]] }}
+  | foreach id from exp1 downto exp2 exp3               :: S :: fordownbyone  {{ icho [[ foreach id from exp1 downto exp2 by 1 exp4 ]] }}
+
 % vectors
   | [ exp1 , ... , expn ]                             :: :: vector {{ com vector (indexed from 0) }}
 % order comes from global command-line option???