Cover all remaining statements and expressions in the spec

[cburgdorf]

What was wrong?

The spec didn't cover all statements and expressions of the language.

How was it fixed?

Added basic coverage of all statements and expressions plus a few extra goodies

[codecov-commenter]

Codecov Report

Merging #514 (1a5e939) into master (a0821aa) will not change coverage.
The diff coverage is n/a.

❗ Current head 1a5e939 differs from pull request most recent head 9d0a748. Consider uploading reports for the commit 9d0a748 to get more accurate results

@@           Coverage Diff           @@
##           master     #514   +/-   ##
=======================================
  Coverage   87.51%   87.51%           
=======================================
  Files          86       86           
  Lines        5550     5550           
=======================================
  Hits         4857     4857           
  Misses        693      693           

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[cburgdorf]

Btw, I'm going to add a CI check to ensure our code examples won't go out of date soon but that will be a different PR.

[cburgdorf]

Ok, I ended up adding the CI check to this PR (but happy to move it out on request) and it already found a few code examples that were out of date.

[g-r-a-n-t]

Looks great. I love that we check the snippets now.

[g-r-a-n-t]

hmm.. looks like the parser is letting func defs without parens through

[cburgdorf]

Oh yeah, looks like the parser only disallows missing parens if the function name is immediately followed by a : and hence declares no return type. I filed an issue: #523