# nhc98 error messages

### What does this error message mean?

Like all compilers, the error messages produced by the nhc98 are sometimes difficult to understand. Here are a few tips as to what might have gone wrong.

`Only 32 words after gc, need 32 words`
  The garbage collector failed to reclaim enough space - the program is out of heap. Try re-running with +RTS -Hn -RTS where n is a bigger heap size, e.g. 16M.
`Type error: cannot unify types Prelude.2 and Prelude.3 at 133:9`
  In type errors, pairs, triples, and other tuples are denoted by their arity - thus Prelude.2 means pair. The notation 133:9 means line 133, character position 9.
`arityIS in IntState.hs couldn't find 376`
  If you get an error message like this and you have an (n+k) pattern in your program, then you have found a bug in the compiler. Please report it!

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10th June 1999
York Functional Programming Group