symbol_actions.js

macro @ {
  case { _ $x } => {
    letstx $sx = [makeValue(unwrapSyntax(#{$x}), #{here})];
    return #{ Symbol.for($sx) }
  }
}

function todoApp(state, action) {
  if (state === undefined) state = initialState;
  switch (action.type) {
  case @SET_VISIBILITY_FILTER:
    return Object.assign({}, state, {
      visibilityFilter: action.filter
    });
  default:
    return state;
  }
}

// compiles to

function todoApp(state, action) {
    if (state === undefined)
        state = initialState;
    switch (action.type) {
    case Symbol.for('SET_VISIBILITY_FILTER'):
        return Object.assign({}, state, { visibilityFilter: action.filter });
    default:
        return state;
    }
}