Hi, "Hat": The Haskell Tracer. http://www.haskell.org/hat/ >From the site: Hat helps locating errors in programs. Furthermore, it is useful for understanding how a (correct) program works, especially for teaching and program maintenance. Hat is not a time or space profiler. Hat can be used for programs that terminate normally, that terminate with an error message or that terminate when interrupted by the programmer.
"Vital"/"Pivotal": it's dead, but it may be interesting to you anyway. http://www.cs.kent.ac.uk/projects/pivotal/ http://www.cs.kent.ac.uk/projects/vital/ >From the site: Pivotal has similar goals to its predecessor system, Vital. In particular: * Documents are live in the sense that, if a document is changed, the displayed values are automatically re-evaluated. Thus documents are always in a consistent state. * Direct manipulation of ADT values is supported. That is, an end user is able to manipulate the text of a Haskell module simply by point-and-click mouse operations on displayed values. Pen and paper work too. Ezra. Ulrik Rasmussen-2 wrote: > > Hi all, > > I was wondering if someone has written a tracer/debugger that shows you > how a given Haskell expression is evaluated, by generating all the > intermediate states of the expression until it is in normal form? > > For instance, given the following code: > >> take' 0 xs = [] >> take' n (x:xs) = x : take' (n-1) xs >> exp = take' 2 [1,2,3,4,5,6] > > the trace of 'exp' would generate something like this: > >> exp = take' 2 [1,2,3,4,5,6] >> exp = (\n (x:xs) -> x : take' (n-1) xs) 2 [1,2,3,4,5,6] >> exp = 1 : take' (2-1) [2,3,4,5,6] >> exp = 1 : take' 1 [2,3,4,5,6] >> exp = 1 : (\n (x:xs) -> x : take' (n-1) xs) 1 [2,3,4,5,6] >> exp = 1 : 2 : take' (1-1) [3,4,5,6] >> exp = 1 : 2 : take' 0 [3,4,5,6] >> exp = 1 : 2 : (\0 xs -> []) 0 [3,4,5,6] >> exp = 1 : 2 : [] >> exp = [1,2] > > That is, all the substitutions performed when evaluating 'exp' from left > to right. > > I was thinking that something like this could be rather useful when > teaching or learning Haskell. > > > Thanks, > > Ulrik > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > > -- View this message in context: http://old.nabble.com/Tracer-for-Haskell-showing-substitutions-tp27421880p27424789.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
