Function bind_associative 

pub fn bind_associative(
    pattern: &[Form],
    val: &Value,
    env: &mut Env,
) -> EvalResult<()>

Bind a map destructuring pattern against val in env.

pattern is a flat [key val key val ...] slice from FormKind::Map.

Supports:

• :keys [a b c] — bind symbols from keyword keys :a, :b, :c
• :strs [a b] — bind symbols from string keys "a", "b"
• :syms [a b] — bind symbols from symbol keys 'a, 'b
• :as name — bind the whole value to name
• :or {a default} — default value for missing keys
• Regular {sym :key} direct bindings