A monad allowing one to emit elements of type a. Semantically equivalent to Writer (DList a) r, but:

1. is faster, being based on the Church-encoded free monad
2. implements Monoid, so that all the Data.Foldable convenience is supported
3. has better ergonomics as it doesn't require the user to wrap a values into DLists

This type is also semantically equivalent to Stream (Of a) Identity r.

Useful for monadically creating tree-like structures, for example the following

import Data.Tree
yield = embed . pure
main = putStrLn . drawTree . Node "a" . toList $ do
    yield "b"
    nestWith (Node "c") $ do
        yield "d"
        yield "e"
    yield "f"

will produce

-a
|
+- b
|
+- c
|  |
|  +- d
|  |
|  `- e
|
`- f

Embed the given value into a Layer-like type (either Layer itself or a monad transformer stack with Layer at the bottom).

Collapse the given Layer into a single element by converting it into a list, applying the given function to the result and embedding it back.

A TestTree of tests under some name prefix.

Run a TestNested computation to produce a TestTree (without actually executing the tests).

Descend into a folder.

Descend into a folder for a TestNested computation.

Like testNestedM but adds a subdirectory corresponding to the GHC version being used.

Run a list of TestNested computation to produce a TestTree (without actually executing the tests).

Descend into a folder for a list of tests.

Descend into a folder for a list of TestNested computations.

Like testNested but adds a subdirectory corresponding to the GHC version being used.

Check the contents of a file against a Text.

Check the contents of a file against a Text.

Check the contents of a file against a Doc.

Check the contents of a file against a Doc.

Check the contents of a file under a name prefix against a Text.

Compare the contents of a file under a name prefix against a Text using a predicate.

Check the contents of a file under a name prefix against a Text.

Check the contents of a file under a name prefix against a Text.

Check the contents of a file under a name prefix against a Text.

Given a lists of FilePaths and a filename, concatenate the members of the list together, append the GHC version number, then append the filename. We use this to create GHC-version-dependent golden files.

Asserts that the specified actual value is equal to the expected value. The output message will contain the prefix, the expected value, and the actual value.

If the prefix is the empty string (i.e., ""), then the prefix is omitted and only the expected and actual values are output.

Asserts that the specified actual value is equal to the expected value (with the expected value on the left-hand side).

Asserts that the specified actual value is equal to the expected value (with the actual value on the left-hand side).