feat(users/sterni/nix): move flow.match to string.match

After all it only matches strings.

Change-Id: I3d2e5221ef43f692de69028e78ed98b6b11f82d1
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2586
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>

users/sterni/nix/string/default.nix

@@ -55,6 +55,9 @@ let
       then s
       else pad { inherit char; "${side}" = diff; } s;
 
+  # pattern matching for strings only
+  match = val: matcher: matcher."${val}";
+
 in {
   inherit
     take
@@ -67,5 +70,6 @@ in {
     fromChars
     pad
     fit
+    match
     ;
 }

users/sterni/nix/string/tests/default.nix

@@ -45,9 +45,21 @@ let
       null)
   ];
 
+  dontEval = builtins.throw "this should not get evaluated";
+
+  testMatch = it "tests match" [
+    (assertEq "basic match usage" 42
+      (string.match "answer" {
+        "answer" = 42;
+        "banana" = dontEval;
+        "maleur" = dontEval;
+      }))
+  ];
+
 in
   runTestsuite "nix.string" [
     testTakeDrop
     testIndexing
     testFinding
+    testMatch
   ]