"A collection of methods which use implicit-context sends to implement more
conventional control-flow syntax. The general idea is that the context/block/
method can be considered taking a role in control-flow."

"Usage note: implicit context sends work within other expressions, just
requiring some parentheses to denote the scope of the keyword-sends."

"Implementation note: True and False themselves haven't been dispatched in
their positions, since this can be done with an inliner."

_@(Method traits) if: boolean then: trueBlock
[
  boolean ifTrue: trueBlock
].

_@(Method traits) if: boolean then: trueBlock else: falseBlock
[
  boolean ifTrue: trueBlock ifFalse: falseBlock
].

_@(Method traits) do: body while: testBlock
"Evaluates the body block once, and then again as long as the testBlock
returns True, and returns the last return value of the body."
[| result |
  [result: body do.
   testBlock do] whileTrue.
  result
].

_@(Method traits) do: block until: testBlock
"Evaluates the body block once, and then again as long as the testBlock
returns False, and returns the last return value of the body."
[| result |
  [result: body do.
   testBlock do] whileFalse.
  result
].

_@lobby the: name@(Symbol traits) of: obj
"Answer the value of the slot with the given name in the object.
This implementation is too naive."
[
  obj atSlotNamed: name
].