half-move counter seems to be broken.

[phadej]

Thanks for this awesome library!

I think I found a small bug in move application, the half move counter doesn't seem to reset after pawn moves:

*Game.Chess> doPly startpos (move D2 D4)
"rnbqkbnr/pppppppp/8/8/3P4/8/PPP1PPPP/RNBQKBNR b KQkq d3 1 1"

It should be

"rnbqkbnr/pppppppp/8/8/3P4/8/PPP1PPPP/RNBQKBNR b KQkq d3 0 1"

(FWIW, lichess forget to mark enpassant square, though according to wikipedia

En passant target square in algebraic notation. If there's no en passant target square, this is "-". If a pawn has just made a two-square move, this is the position "behind" the pawn. This is recorded regardless of whether there is a pawn in position to make an en passant capture.

chess.com analysis includes d3).

EDIT: the counter doesn't seem to reset after captures either.

[mlang]

Oleg Grenrus ***@***.***> writes:

Thanks for this awesome library! I think I found a small bug in move application, the half move counter doesn't seem to reset after pawn moves: *Game.Chess> doPly startpos (move D2 D4) "rnbqkbnr/pppppppp/8/8/3P4/8/PPP1PPPP/RNBQKBNR b KQkq d3 1 1"

Ahh, good catch. Question is, should it only reset after *pawn* moves, or after captures as well?

It should be "rnbqkbnr/pppppppp/8/8/3P4/8/PPP1PPPP/RNBQKBNR b KQkq d3 0 1"

-- CYa, ⡍⠁⠗⠊⠕

[phadej]

@mlang The same wikipedia page says

Halfmove clock: The number of halfmoves since the last capture or pawn advance, used for the fifty-move rule.

And the page about the Fifty-move rule

The fifty-move rule in chess states that a player can claim a draw if no capture has been made and no pawn has been moved in the last fifty moves (for this purpose a "move" consists of a player completing a turn followed by the opponent completing a turn). The purpose of this rule is to prevent a player with no chance of winning from obstinately continuing to play indefinitely[1] or seeking to win by tiring the opponent.

[phadej]

Thanks for quick fixes!