Northampton Town fielded three trialists in Tuesday's reserve match with Gillingham, which was drawn 0-0.
Haslam joined Halifax from Sheffield Wednesday last week
In goal for the Cobblers was Southampton's 18-year-old fourth-choice goalkeeper Michael Poke.
Also in the line-up were ex-Cambridge midfielder David Bridges, 21, and former Sheffield Wednesday defender Steven Haslam, 24.
Haslam joined Halifax last week - but was sent off on his debut for the Shaymen at Tamworth on Saturday.