All:
    - multi-line read
    - loop/recur ?
    - hash-maps with non-string keys
    - gensym reader inside quasiquote
    - "intern" symbols, strings and numbers. Simplify equality
      comparision.
    - Contact Peter Norvig about license

    - synchronize function/definitions order/names in files
    - move Env into separate file (maybe)?
    - more metadata tests
    - more hash_map tests
        - hash-map with space in key string (make)
    - more interop tests
    - support metadata on symbol, hash-map, list, vector, function, atom

    - unindent tco while loop for step5-A

---------------------------------------------

JS:

Python:

Clojure:

C:
    - come up with better way to do 20 vararg code

Bash:

PHP:

Make:
    - Norvig2: TCO/recur?
    - allow '_' in make variable names
    - errors should propagate up from within load-file


Mal:
    - line numbers in errors
    - step6: command line arguments
    - step 5
    - step 9

Java:
    - vectors, hash-maps, metadata
    - step 9
    - mvn exec:java -Dexec.mainClass="mal.step6_file" -Dexec.args="incC.mal"

Rust:
    - http://www.rustforrubyists.com/book/index.html
    - http://static.rust-lang.org/doc/0.9/complement-cheatsheet.html
    - http://pzol.github.io/getting_rusty/
    - readline:
        - http://redbrain.co.uk/2013/11/09/rust-and-readline-c-ffi/
        - http://www.reddit.com/r/rust/comments/1q9pqc/rust_cffi_and_readline/
        - https://github.com/dbp/rustrepl
    - hash-map:
        - http://static.rust-lang.org/doc/master/std/hashmap/index.html
        - http://static.rust-lang.org/doc/master/std/hashmap/struct.HashMap.html
    - vector/list:
        - http://static.rust-lang.org/doc/master/std/vec/index.html
    - steps 2-A


Others (based on redmonk languages from Jan 2014): ?
    http://sogrady-media.redmonk.com/sogrady/files/2014/01/lang-rank-114-wm.png
    
    - Tier 1
        * JavaScript
        * Java
        * PHP
        ? C#
        * Python
        ? C++
        - Ruby
        * C
        - Objective-C
        - Perl 
        * Shell

    - Tier 2
        * Clojure
        ? Go
        ? Assembly
        ? Fortan
        ? Dart
        ? D

    - Tier 3
        ? Pascal
        - Rust
    -