Make recSelError generate the standard part of the record selector
error message (i.e. "No match in record selector") rather than have
that string duplicated for every record selector.
nonExhaustiveGuardsError, patError, noMethodBindingError
:: Addr# -> a -- All take a UTF8-encoded C string
-recSelError s = throw (RecSelError (unpackCStringUtf8# s)) -- No location info unfortunately
-runtimeError s = error (unpackCStringUtf8# s) -- No location info unfortunately
+recSelError s = throw (RecSelError ("No match in record selector "
+ ++ unpackCStringUtf8# s)) -- No location info unfortunately
+runtimeError s = error (unpackCStringUtf8# s) -- No location info unfortunately
nonExhaustiveGuardsError s = throw (PatternMatchFail (untangle s "Non-exhaustive guards in"))
irrefutPatError s = throw (PatternMatchFail (untangle s "Irrefutable pattern failed for pattern"))