Expressions in HAC depart somewhat from CAST style and follow from ANSI C grammar more closely. Here we list a few differences.
The equality operator in CAST was =,
but C and HAC use ==.
However, use of the deprecated = operator is allowed
if the expression is wrapped in parentheses, e.g. (x=y).
Less-than '<' and greater-than '>' operators now need to be parenthesized
to dismbiguate them from template parameter delimiters, See Templates.
For example, in CAST,
[ X<Y -> ... ]
would need to be re-written in HAC
[ (X<Y) -> ... ].
Logical operators in CAST were & and |, but in C and HAC, they are respectively && and ||. This makes way for bitwise operators (on integers) & and |.
XOR (bitwise integer) is ^ in HAC.
Logical XOR (for booleans) current uses != instead of ^, however, overloading ^ might be added back at some point.
The standard boolean and integer operations are strictly type-checked. At compile-time, there is no implicit conversion between pbool and pint values. For example, one cannot use an integer expression as a boolean, whereas in C, the integer is implicitly compared against 0.
Explicit casting operators may be added in the future.
Function expressions may be added in the future.