ImplLooping

From dis-Emi-A

Looping

Looping is a unification of both traditional loops and of if statements. Refer to Booleans for how this combines the value types of Boolean/Set.

A loop looks like this:

{{{ [ var in condition ] {

 body;

}; }}}

AutoTyping Code

The condition must evaluate to a Set type. This will serve as the short-hand for the pseudo-code evaluation:

{{{ iter = iter_begin( condition ); while( true ) {

 if( iter_end( iter ) )
   break;

 var = iter_value( iter );
 body( var );
 iter = iter_next( iter );

} }}}

The functions in this pseudo-code will actually be called*. Therefore when we say Set type all we really need is this set of functions:

iter_begin 

returns a starting iterator for the set

iter_end 

determines if the iterator is in the end position (past final element)

iter_value 

returns the value indexed by the iterator

iter_next 

returns a new iterator refering to the next item

The return value of all items is open, except for iter_end, which must return a Boolean type. Which means that in the strictest sense we need the loop to evaluate it again (making an endless loop). So we'll have to assume the compiler has a special understand of a true Boolean type and only needs the above expansion in cases where it isn't Boolean.

• That is for the purpose of auto-typing, the emitter may choose to not call these exact functions, or in this order, should it have a better method (especially for the Boolean type itself). So in respect to the previous paragraph, these functions still need to be defined for Boolean because until auto-typing is finished the Compiler won't know for sure what the type is.

Boolean Iteration

The boolean form of the functions would look like this then:

iter_begin :> :Boolean: b -> b iter_end :> :Boolean: b -> !b iter_value :> :Boolean: b -> b iter_next :> :Boolean: b -> false

Easy enough. :)