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Here's a typical simple type error from GHC:

Derive/Call/India/Pakhawaj.hs:142:62:
    Couldn't match type ‘Text’ with ‘(a1, Syllable)’
    Expected type: [([(a1, Syllable)], [Sequence Bol])]
      Actual type: [([Syllable], [Sequence Bol])]
    Relevant bindings include
      syllables :: [(a1, Syllable)]
	(bound at Derive/Call/India/Pakhawaj.hs:141:16)
      best_match :: [(a1, Syllable)]
		    -> Maybe (Int, ([(a1, Syllable)], [(a1, Sequence Bol)]))
	(bound at Derive/Call/India/Pakhawaj.hs:141:5)
    In the second argument of ‘mapMaybe’, namely ‘all_bols’
    In the second argument of ‘($)’, namely
      ‘mapMaybe (match_bols syllables) all_bols’

The order of sections is "couldn't match", "expected actual", "relevant bindings", "context" (in the second argument etc.). I think it would be easier to read as "couldn't match", "expected actual", "context", "bindings", and with a * to mark each section:

Derive/Call/India/Pakhawaj.hs:142:62:
  * Couldn't match type ‘Text’ with ‘(a1, Syllable)’
    Expected type: [([(a1, Syllable)], [Sequence Bol])]
      Actual type: [([Syllable], [Sequence Bol])]
  * In the second argument of ‘mapMaybe’, namely ‘all_bols’
    In the second argument of ‘($)’, namely
      ‘mapMaybe (match_bols syllables) all_bols’
  * Relevant bindings include
      syllables :: [(a1, Syllable)]
	(bound at Derive/Call/India/Pakhawaj.hs:141:16)
      best_match :: [(a1, Syllable)]
		    -> Maybe (Int, ([(a1, Syllable)], [(a1, Sequence Bol)]))
	(bound at Derive/Call/India/Pakhawaj.hs:141:5)

I'm sure there are plenty of other sections that don't show up in this simple example, in any case they should go from most to least critical and be marked off with a *.

Trac metadata

Trac field	Value
Version	7.11
Type	FeatureRequest
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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