Parsing and generation of dictionaries

[JSAbrahams]

Relevant issues

• Do not merge before #439
• Made note of #443
• Resolves #414

Summary

• Add parsing of dictionaries
• Add dictionary type skeleton to context:
  • iterator returning types
  • keys() method which returns iterator where __next__() has key return type
  • values() method which returns iterator where __next__() has value return type
• Check of dictionaries

Added Tests

Happy

• Parse dictionary.
• Parse dictionary builder.
• Dictionary with multiple types.

Sad

• Dictionary with types other than signature.
• Access dictionary entries with wrong key type.
• Access dictionary and have use value incorrectly (assume it is other type).
• Access dictionary and have use value incorrectly (assume it is key type).
• Index dictionary using slice
• index set

[codecov[bot]]

Codecov Report

Merging #438 (0a2937e) into develop (f1b0646) will increase coverage by 0.01%. The diff coverage is 87.50%.

@@             Coverage Diff             @@
##           develop     #438      +/-   ##
===========================================
+ Coverage    88.16%   88.17%   +0.01%     
===========================================
  Files          105      105              
  Lines        11391    11497     +106     
===========================================
+ Hits         10043    10138      +95     
- Misses        1348     1359      +11     

Impacted Files	Coverage Δ
src/check/constrain/constraint/mod.rs	91.89% <ø> (-2.45%)	:arrow_down:
src/check/constrain/unify/function.rs	77.55% <0.00%> (ø)
src/check/context/function/python.rs	96.87% <ø> (ø)
src/generate/ast/node.rs	75.37% <0.00%> (-0.39%)	:arrow_down:
src/parse/ast/node.rs	81.16% <0.00%> (-0.40%)	:arrow_down:
src/check/context/function/mod.rs	52.00% <25.00%> (ø)
src/check/ast/mod.rs	67.28% <50.00%> (-0.33%)	:arrow_down:
src/generate/ast/mod.rs	93.91% <69.23%> (-1.29%)	:arrow_down:
src/check/context/clss/mod.rs	85.53% <75.00%> (-1.81%)	:arrow_down:
src/generate/convert/builder.rs	76.92% <81.81%> (+1.92%)	:arrow_up:
... and 20 more