Diff

Diff algorithm in pure Haskell

https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.4.6927

LTS Haskell 23.5:0.5@rev:1
Stackage Nightly 2025-01-21:1.0.2
Latest on Hackage:1.0.2

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BSD-3-Clause licensed by Sterling Clover
Maintained by David Fox
This version can be pinned in stack with:Diff-1.0.2@sha256:39d55f9d86e54939b7cf443fb3a3970d98341073dfda7d52cfa9bc6562f139d9,1581

Module documentation for 1.0.2

Depends on 3 packages(full list with versions):
array, base, pretty

Implementation of the standard diff algorithm in Haskell.

Time complexity is O(ND) (input length * number of differences). Space complexity is O(D^2). Includes utilities for pretty printing.

Changes

1.0.2

  • Output correct format when an input file is empty, e.g. @@ --0,0 +1,3 @@.

1.0.1.1

  • Require base >= 4.11 (GHC 8.4).

1.0

  • Add Unix diff style annotations to output of prettyContextDiff, e.g @@ -1,5 +1,4 @@. This required three changes to the signature of getContextDiff due to the addition of a wrapper type Numbered, which enumerates the elements of the input list.

  • Signature change 1: The element pretty printer type changes from (a -> Doc) to (Numbered a -> Doc). An unnumber function is provided so that the old behavior can be obtained by changing that argument from pretty to (pretty . unnumber)

  • Signature change 2: The result type of getContextDiff changes from ContextDiff a to ContextDiff (Numbered a). A function unNumberContextDiff is provided to convert the result back to the old type.

  • Signature change 3: the context argument is now Maybe Int rather than Int, reflecting the change made to getContextDiffNew in 0.5.

  • A prettyContextDiffOld function is provided to get the old style output.

  • The old broken version of getContextDiffOld is removed.

  • Document the behavior of groupBy'.

0.5

  • Bring space complexity down to D^2 (Bodigrim).
  • Add Bifunctor instance (Jonathan King). Requires base >= 4.8.
  • Fix for the grouped context diff. It was omitting all trailing contexts.
  • Allow unlimited number of context elements (getContextDiffNew).

0.4

  • Generalize Diff a to PolyDiff a b. Diff has been replaced with a specialized synonym type Diff a = PolyDiff a a, but it’s still not backward compatible if you imported Diff(..).