def taken

bend-lint-rules@0.2.0.0 · language/decreasing_call.bend:86

import Base
import bend-lint-api@0.2.0.0/linter/lint.bend as Lint
import bend-lint-api@0.2.0.0/shared/lists.bend as Lists

86# What a case's patterns take apart: each pattern, a constructor, makes its variables smaller than its
87# scrutinee, and than all that scrutinee is smaller than.
88def taken(
89  scrutinees: List<&2, Lint.Node>,
90  patterns: List<&2, Lint.Node>,
91  +smaller: List<&2, Smaller>
92) -> List<&2, Smaller>:
93  match scrutinees patterns:
94    case Con{
95      Lint.Node{Lint.Variable{s}, n, sp, k, f},
96      more
97    } Con{Lint.Node{Lint.PatternConstructor{t}, pn, ps, kids, pf}, rest}:
98      taken(
99        more,
100        rest,
101        Lists.onto(
102          &2,
103          Smaller,
104          pairs(roots(smaller, s, []), Lint.Node.bound(kids, []), []),
105          smaller
106        )
107      )
108    case Con{x, more} Con{y, rest}:
109      taken(more, rest, smaller)
110    case _ _:
111      smaller