PatternMatchPushDown(S, A, B)

patmatch1.spad line 311 [edit on github]

• S: SetCategory

• A: PatternMatchable S

• B: Join(SetCategory, RetractableTo A)

This packages provides tools for matching recursively in type towers.

fixPredicate: (B -> Boolean) -> A -> Boolean

fixPredicate(f) returns g defined by g(a) = f(a::B).

patternMatch: (A, Pattern S, PatternMatchResult(S, B)) -> PatternMatchResult(S, B)

patternMatch(expr, pat, res) matches the pattern pat to the expression expr; res contains the variables of pat which are already matched and their matches. Note: this function handles type towers by changing the predicates and calling the matching function provided by A.