// Function application. Execute the first AST and verify that it is a
// function. Then call that function's apply method.
@Override
public Val exec(Env env) {
Val fun = _asts[0].exec(env);
if (!fun.isFun())
throw new IllegalArgumentException("Expected a function but found " + fun.getClass());
AST ast = ((ValFun) fun)._ast;
int nargs = ast.nargs();
if (nargs != -1 && nargs != _asts.length)
throw new IllegalArgumentException(
"Incorrect number of arguments; '"
+ ast
+ "' expects "
+ nargs
+ " but was passed "
+ _asts.length);
try (Env.StackHelp stk = env.stk()) {
return stk.returning(ast.apply(env, stk, _asts));
}
}
