Difference b/w apply(),applyComponent,For Each loop

Question

Hi , 
 
 Can anyone share some good example to differentiate b/w apply(),applyComponent,For Each loop. 
 
 Please don't share any documentation link as i am not getting clarity by seeing that. 
 
 If possible plz use any small dataset to give an example. This always confuse which one i should use on what scenario.

ravalik · Answer

Hi sauravk, 
 
apply( )-Calls a rule or function for each item in a list, and provides any contexts specified. 
 
Ex: apply(fn!sum, {1, 2, 3}, 2) returns 3; 4; 5 This is the simple example for apply function. 
 
forEach( )- Evaluates the provided expression once for every item and returns an array of the results. 
Ex: 
a!forEach( 
 items: {"January", "February", "March"}, 
 expression: with( 
 local!month: fv!item, 
 a!forEach( 
 items: {1, 2}, 
 expression: local!month & " " & fv!item 
 ) 
 ) 
) 
 
output: {"January 1", "January 15"}, {"February 1", "February 15"}, and {"March 1", "March 15"} 
 
applyComponents: calls a rule for each item in an array and returns an array of the results. 
 a!applyComponents() is applicable when you're iterating over a list of components or iterating over a rule that has a load() within it, 
 
Ex: a!applyComponents( 
 function: fn!isnull, 
 array: { 
 1, 
 5, 
 null, 
 6, 
 null, 
 8 
 } 
) 
 
O/p: 
 false false true false true false 
 
Thanks, 
ravalik