1.2 code conditionals - RawIron/rawiron.github.io GitHub Wiki

if or guards

it is a predicate and a block of statements

if <predicate> <block>

| <predicate> <block>
| <predicate> <block>
| otherwise   <block>

as a function which has (predicate, function) as parameters

as an example here is an if statement:

funds = 20
withdraw = 12
if(sufficientFunds) { funds -= withdraw }

replace the block of statements with an anonymous function

myScope = {
  funds = 20
  withdraw = 12
}
if(sufficientFunds) { &scope => scope.funds -= scope.withdraw }

the scope can contain functions

myScope = {
  funds = 20
  withdraw(amount) { funds -= amount }
}
if(sufficientFund, &scope => { scope.withdraw(12) })

implementation of the if function:

  • the challenge is that if has to work for any type of scope
def (myScope) if(predicate, func) newScope =
  when(predicate) = func(myScope)
  otherwise = myScope

pattern matching

case <data variable> of <data constructor> <block>

The case statement can have an interesting variation.

case <predicate> of
 True  <block>
 False <block>
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