Move maybe-set-at to assocs

basis/compiler/cfg/stack-analysis/stack-analysis.factor

@@ -278,9 +278,6 @@ ERROR: cannot-merge-poisoned states ;
 : block-in-state ( bb -- states )
     dup predecessors>> state-out get '[ _ at ] map merge-states ;
 
-: maybe-set-at ( value key assoc -- changed? )
-    3dup at* [ = [ 3drop f ] [ set-at t ] if ] [ 2drop set-at t ] if ;
-
 : set-block-in-state ( state bb -- )
     [ clone ] dip state-in get set-at ;
 

core/assocs/assocs-tests.factor

@@ -142,3 +142,7 @@ unit-test
 
 [ 1 f ] [ 1 H{ } ?at ] unit-test
 [ 2 t ] [ 1 H{ { 1 2 } } ?at ] unit-test
+
+[ f ] [ 1 2 H{ { 2 1 } } maybe-set-at ] unit-test
+[ t ] [ 1 3 H{ { 2 1 } } clone maybe-set-at ] unit-test
+[ t ] [ 3 2 H{ { 2 1 } } clone maybe-set-at ] unit-test

core/assocs/assocs.factor

@@ -22,6 +22,9 @@ M: assoc assoc-like drop ;
 : ?at ( key assoc -- value/key ? )
     2dup at* [ 2nip t ] [ 2drop f ] if ; inline
 
+: maybe-set-at ( value key assoc -- changed? )
+    3dup at* [ = [ 3drop f ] [ set-at t ] if ] [ 2drop set-at t ] if ;
+
 <PRIVATE
 
 : (assoc-each) ( assoc quot -- seq quot' )