.TH "Diffing_with_keys" 3 2024-02-29 OCamldoc "OCaml library"
.SH NAME
Diffing_with_keys \- When diffing lists where each element has a distinct key, we can refine the diffing patch by introducing two composite edit moves: swaps and moves.
.SH Module
Module   Diffing_with_keys
.SH Documentation
.sp
Module
.BI "Diffing_with_keys"
 : 
.B sig end

.sp
When diffing lists where each element has a distinct key, we can refine
the diffing patch by introducing two composite edit moves: swaps and moves\&.
.sp

.ft B
Swap
.ft R
s exchange the position of two elements\&. 
.ft B
Swap
.ft R
cost is set to
.ft B
2 * change \- epsilon
.ft R
\&.
.ft B
Move
.ft R
s change the position of one element\&. 
.ft B
Move
.ft R
cost is set to
.ft B
delete + addition \- epsilon
.ft R
\&.
.sp
When the cost 
.ft B
delete + addition
.ft R
is greater than 
.ft B
change
.ft R
and with those
specific weights, the optimal patch with 
.ft B
Swap
.ft R
s and 
.ft B
Move
.ft R
s can be computed
directly and cheaply from the original optimal patch\&.

.sp

.sp
.sp
.I type 
.B 'a
.I with_pos 
= {
 pos : 
.B int
;
 data : 
.B 'a
;
 }

.sp

.sp

.I val with_pos 
: 
.B 'a list -> 'a with_pos list
.sp

.sp
.I type 
.B ('l, 'r, 'diff)
.I mismatch 
=
 | Name
.B of {
 pos : 
.B int
;
 got : 
.B string
;
 expected : 
.B string
;
 types_match : 
.B bool
;
 }
 | Type
.B of {
 pos : 
.B int
;
 got : 
.B 'l
;
 expected : 
.B 'r
;
 reason : 
.B 'diff
;
 }
 
.sp

.sp
.I type 
.B ('l, 'r, 'diff)
.I change 
=
 | Change
.B of 
.B ('l, 'r, 'diff) mismatch
 | Swap
.B of {
 pos : 
.B int * int
;
 first : 
.B string
;
 last : 
.B string
;
 }
 | Move
.B of {
 name : 
.B string
;
 got : 
.B int
;
 expected : 
.B int
;
 }
 | Insert
.B of {
 pos : 
.B int
;
 insert : 
.B 'r
;
 }
 | Delete
.B of {
 pos : 
.B int
;
 delete : 
.B 'l
;
 }
 
.sp
This specialized version of changes introduces two composite
changes: 
.ft B
Move
.ft R
and 
.ft B
Swap
.ft R


.sp

.I val prefix 
: 
.B Format.formatter -> ('l, 'r, 'diff) change -> unit
.sp

.sp
.I module Define : 
.B functor (D : sig end) -> sig end

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