trace :: forall a b. DebugWarning => a -> (Unit -> b) -> b
Log any PureScript value to the console for debugging purposes and then
return a value. This will log the value's underlying representation for
low-level debugging, so it may be desireable to
show the value first.
The return value is thunked so it is not evaluated until after the message has been printed, to preserve a predictable console output.
doSomething = trace "Hello" \_ -> ... some value or computation ...
spyWith :: forall a b. DebugWarning => String -> (a -> b) -> a -> a
spy, but allows a function to be passed in to alter the value
that will be printed. Useful in cases where the raw printed form of a value
is inconvenient to read - for example, when spying on a
Array.fromFoldable here will print it in a more useful form.
debugger :: forall a. DebugWarning => (Unit -> a) -> a
Triggers any available debugging features in the current runtime - in a web browser with the debug tools open, this acts like setting a breakpoint in the script. If no debugging feature are available nothing will occur, although the passed contination will still be evaluated.
Generally this works best by passing in a block of code to debug as the continuation argument, as stepping forward in the debugger will then drop straight into the passed code block.