title: Putting key-values into map conditionally, what are the concise ways?
body: <p>What are the concise/ elegant ways to put into a map key-value pairs for which the corresponding conditions are true? </p>
  
  <p>That is to translate </p>
  
  <pre><code>[condition1 condition2 ...] [key1 val1 key2 val2 ...]
  </code></pre>
  
  <p>or</p>
  
  <pre><code>[condition1 condition2 ...] [key1 key2 ...] [val1 val2 ...]
  </code></pre>
  
  <p>or</p>
  
  <pre><code>[condition1 key1 val1 condition2 key2 val2...]
  </code></pre>
  
  <p>into</p>
  
  <pre><code>{key-for-true-condition1 val-for-true-condition1, key-for-true-condition2 val-for-true-condition2...}
  </code></pre>
  
  <p>I think to use "reduce" with "if" in its lambda but interested in more concise/ beautiful/ elegant/ idiomatic ways.</p>