Pretty-print values in the REPL

Pretty-print values in the REPL by printing each item in a list or
attrset on a separate line. When possible, single-item lists and
attrsets are printed on one line, as long as they don't contain a nested
list, attrset, or thunk.

Before:
```
{ attrs = { a = { b = { c = { }; }; }; }; list = [ 1 ]; list' = [ 1 2 3 ]; }
```

After:
```
{
  attrs = {
    a = {
      b = {
        c = { };
      };
    };
  };
  list = [ 1 ];
  list' = [
    1
    2
    3
  ];
}
```

(cherry picked from commit c0a15fb7d03dfb8f53bc6726c414bc88aa362592)
Change-Id: Ia2b41849165a5ddb63f7a8c272a2476b3e4292df

2 files changed, 64 insertions, 7 deletions

diff --git a/tests/functional/lang/eval-fail-bad-string-interpolation-4.err.exp b/tests/functional/lang/eval-fail-bad-string-interpolation-4.err.exp
index 5119238d7..6f907106b 100644
--- a/tests/functional/lang/eval-fail-bad-string-interpolation-4.err.exp
+++ b/tests/functional/lang/eval-fail-bad-string-interpolation-4.err.exp
@@ -6,4 +6,4 @@ error:
              |   ^
            10|
 
-       error: cannot coerce a set to a string: { a = { a = { a = { a = "ha"; b = "ha"; c = "ha"; d = "ha"; e = "ha"; f = "ha"; g = "ha"; h = "ha"; j = "ha"; }; «4294967295 attributes elided»}; «4294967294 attributes elided»}; «4294967293 attributes elided»}
+       error: cannot coerce a set to a string: { a = { a = { a = { a = "ha"; b = "ha"; c = "ha"; d = "ha"; e = "ha"; f = "ha"; g = "ha"; h = "ha"; j = "ha"; }; «4294967295 attributes elided» }; «4294967294 attributes elided» }; «4294967293 attributes elided» }
diff --git a/tests/functional/repl.sh b/tests/functional/repl.sh
index 0921edc0f..3765fb492 100644
--- a/tests/functional/repl.sh
+++ b/tests/functional/repl.sh
@@ -151,29 +151,86 @@ echo "$replResult" | grepQuiet -s afterChange
 # Normal output should print attributes in lexicographical order non-recursively
 testReplResponseNoRegex '
 { a = { b = 2; }; l = [ 1 2 3 ]; s = "string"; n = 1234; x = rec { y = { z = { inherit y; }; }; }; }
-' '{ a = { ... }; l = [ ... ]; n = 1234; s = "string"; x = { ... }; }'
+' \
+'{
+  a = { ... };
+  l = [ ... ];
+  n = 1234;
+  s = "string";
+  x = { ... };
+}
+'
 
 # Same for lists, but order is preserved
 testReplResponseNoRegex '
 [ 42 1 "thingy" ({ a = 1; }) ([ 1 2 3 ]) ]
-' '[ 42 1 "thingy" { ... } [ ... ] ]'
+' \
+'[
+  42
+  1
+  "thingy"
+  { ... }
+  [ ... ]
+]
+'
 
 # Same for let expressions
 testReplResponseNoRegex '
 let x = { y = { a = 1; }; inherit x; }; in x
-' '{ x = «repeated»; y = { ... }; }'
+' \
+'{
+  x = { ... };
+  y = { ... };
+}
+'
 
 # The :p command should recursively print sets, but prevent infinite recursion
 testReplResponseNoRegex '
 :p { a = { b = 2; }; s = "string"; n = 1234; x = rec { y = { z = { inherit y; }; }; }; }
-' '{ a = { b = 2; }; n = 1234; s = "string"; x = { y = { z = { y = «repeated»; }; }; }; }'
+' \
+'{
+  a = { b = 2; };
+  n = 1234;
+  s = "string";
+  x = {
+    y = {
+      z = {
+        y = «repeated»;
+      };
+    };
+  };
+}
+'
 
 # Same for lists
 testReplResponseNoRegex '
 :p [ 42 1 "thingy" (rec { a = 1; b = { inherit a; inherit b; }; }) ([ 1 2 3 ]) ]
-' '[ 42 1 "thingy" { a = 1; b = { a = 1; b = «repeated»; }; } [ 1 2 3 ] ]'
+' \
+'[
+  42
+  1
+  "thingy"
+  {
+    a = 1;
+    b = {
+      a = 1;
+      b = «repeated»;
+    };
+  }
+  [
+    1
+    2
+    3
+  ]
+]
+'
 
 # Same for let expressions
 testReplResponseNoRegex '
 :p let x = { y = { a = 1; }; inherit x; }; in x
-' '{ x = «repeated»; y = { a = 1; }; }'
+' \
+'{
+  x = «repeated»;
+  y = { a = 1 };
+}
+'