::SHE+ILA:: Branches and Conditionals

More about ::SHE+ILA:: Branches and Conditionals

In ::SHE+ILA:: we can write a multi-branch selection (a SWITCH or CASE statement) using subscripting of an array of lambdas, each constituting a "branch" of the statement. For example :
(ttyout "woo", ttyout "yay", ttyout "squee") [chooser];
Here, if chooser is 1 we print "woo", if it is 2 we print "yay", and if it is 3 we print "squee". Note that ::SHE+ILA:: is ORIGIN 1 indexed, unlike C++ which is ORIGIN 0 indexed. In fact, element 0 of any Buf is its (read-only) symbol table, giving the plain-text names of its fields (members). Indexing beyond 3 will select 1 again, and indexing below 0 will select from the end of the Buf, i.e. Modulo arithmetic is used by the subscripting operation.
To implement "if then else" we code as follows :
(&falseaction, &trueaction) [1+condition];
so that when condition is .false. (0), the subscript is 1 and falseaction is run, whereas if condition is .true. (1) then the subscript is 2 and trueaction runs.
For a plain "if" with no "else" we have some syntactic sugar : we write (&whatever)[?condition?]; which behaves as if we had written (&$FF, &whatever)[1+condition];
$FF is a "do nothing" false action (see "F"), which pads the false branch.
Loops are coded as {* condition : action *}; where action is run repeatedly while condition is true. The asterisks come from Jackson Structured Programming (JSP).