Add more information to default where: block check names

[jpolitz]

All check blocks come with a default name.

For where blocks, it is simply a copy of the function name.

With new CLI options like --checks "only:<pat>" that do substring matching, it's useful to have more information in these names. For example, a common case in an autograder might involve matching the name of a test case to express ``the name of the where block for the function called f''.

This changes the where block naming from:

file:///Users/joe/src/pyret-lang/test.arr:3:0-7:3: f (0/1)

  line 6, column 2: failed because:
    Values not equal 6 8

Passed: 0; Failed: 1; Ended in Error: 0; Total: 1

to:

file:///Users/joe/src/pyret-lang/test.arr:3:0-7:3: f() where block (0/1)

  line 6, column 2: failed because:
    Values not equal 6 8

Passed: 0; Failed: 1; Ended in Error: 0; Total: 1

[jpolitz]

@shriram @dbp @blerner bikeshed away

[jpolitz]

Just to be clear the above is the CLI output for

fun f(x):
  x + 1
where:
  f(5) is 8
end

[dbp]

Is there already a convention in errors and messages whether the : is included when referencing types of blocks? My inclination would be to say f() where: block (as you did in the PR title 😉) but if the convention is to not include : then ignore me.

[blerner]

Obvious argument: () is misleading as it's not the signature of the function

Obvious counterargument: should the test name include the names of the function arguments? In examplar situations, that parameter names might not be stable/consistent.

At minimum, I'd write (...) instead, but I wonder what a useful middle-ground might be for making the function header more accurate in these test names.