trace -package:base is:exact -package:base-prelude

Compute the trace of a matrix

>>> trace (V2 (V2 a b) (V2 c d))
a + d

Output a debug message to sterr, using trace, if tracing is enabled. Note: this writes to stderr even in pure instances.

apply a trace arrow and issue message to stderr

Warning: trace remains in code

Warning: trace remains in code

Lens onto the Trace of a QDiagram.

Log a message.

Warning: Trace statement left in code

Internally log what occurred. Log will be re-played on failure.

see trace

Sum of the elements in the diagonal. See also getDiag. Example:

( 1 2 3 )
( 4 5 6 )
trace ( 7 8 9 ) = 15

Warning: Leaving traces in the code

Lens onto the Trace of a QDiagram.

Apply a monadic function to each element flowing through the stream and discard the results.

>>> Stream.drain $ Stream.trace print (Stream.enumerateFromTo 1 2)
1
2

Compare with tap.

Deprecated: Don't leave me in the code

Append a message to the trace log.

Apply a monadic function to each element flowing through the stream and discard the results.

>>> s = Stream.enumerateFromTo 1 2

>>> Stream.fold Fold.drain $ Stream.trace print s
1
2

Compare with tap.

Apply a monadic function to each element flowing through and discard the results.

>>> Stream.fold (Fold.trace print Fold.drain) $ (Stream.enumerateFromTo (1 :: Int) 2)
1
2

>>> trace f = Fold.lmapM (Fold.tracing f)

Pre-release