diff options
| -rw-r--r-- | lib/debug.nix | 22 | ||||
| -rw-r--r-- | lib/default.nix | 2 |
2 files changed, 23 insertions, 1 deletions
diff --git a/lib/debug.nix b/lib/debug.nix index ea6aed60ab43..e3ca3352397e 100644 --- a/lib/debug.nix +++ b/lib/debug.nix @@ -148,6 +148,28 @@ rec { /* A combination of `traceVal` and `traceSeqN`. */ traceValSeqN = traceValSeqNFn id; + /* Trace the input and output of a function `f` named `name`, + both down to `depth`. + + This is useful for adding around a function call, + to see the before/after of values as they are transformed. + + Example: + traceFnSeqN 2 "id" (x: x) { a.b.c = 3; } + trace: { fn = "id"; from = { a.b = {…}; }; to = { a.b = {…}; }; } + => { a.b.c = 3; } + */ + traceFnSeqN = depth: name: f: v: + let res = f v; + in lib.traceSeqN + (depth + 1) + { + fn = name; + from = v; + to = res; + } + res; + # -- TESTING -- diff --git a/lib/default.nix b/lib/default.nix index f985266ed938..803f1f765647 100644 --- a/lib/default.nix +++ b/lib/default.nix @@ -130,7 +130,7 @@ let assertMsg assertOneOf; inherit (self.debug) addErrorContextToAttrs traceIf traceVal traceValFn traceXMLVal traceXMLValMarked traceSeq traceSeqN traceValSeq - traceValSeqFn traceValSeqN traceValSeqNFn traceShowVal + traceValSeqFn traceValSeqN traceValSeqNFn traceFnSeqN traceShowVal traceShowValMarked showVal traceCall traceCall2 traceCall3 traceValIfNot runTests testAllTrue traceCallXml attrNamesToStr; inherit (self.misc) maybeEnv defaultMergeArg defaultMerge foldArgs |