different serializations for functions from codebase vs scratch file?

[aryairani]

In ucm 0.5.40 and earlier, we see a different serialized output from serial-test-04.md depending on whether the mkTestCase definition is in the latest type checked unison file or not. ¹

e.g.

``` unison :hide

mutual0 = cases
  0 -> "okay"
  n ->
    _ = openFile
    mutual1 (drop n 1)

mutual1 n =
  mutual0 n

mkTestCase = do
  saveTestCase "case-04" "v4" mutual1 5
```

``` ucm
scratch/main> run mkTestCase
```

produces a larger serialized output than

``` unison :hide

mutual0 = cases
  0 -> "okay"
  n ->
    _ = openFile
    mutual1 (drop n 1)

mutual1 n =
  mutual0 n

mkTestCase = do
  saveTestCase "case-04" "v4" mutual1 5
```

``` ucm
scratch/main> add
```

``` unison
x = 17
```

```ucm
scratch/main> run mkTestCase
```

Why is the serialized output bigger than it needs to be?

Footnotes

1. This showed up while testing make add an alias of update #5705, which replaced add with update, because update clears the TUF while add didn't. ↩

[aryairani]

Not sure if related, but @stew observed a longer startup time when running a program when there was also a large definition in the scratch file. cc @mitchellwrosen