/ combinators (nb: initial blank to recognize)

X:+((`B         ;{ [x;y;z]({};x;({};y;z))}                               )
    (`C         ;{ [x;y;z]({};({};x;z);y)}                               )
    (`I         ;{ [x]x}                                                 )
    (`K         ;{ [x;y]x}                                               )
    (`S         ;{ [x;y;z]p:S z;({};({};x;p);({};y;p))}                  )
    (`U         ;{ [x;y]p:S y;({};({};x;({};{`head};p));({};{`tail};p))} )
    (`Y         ;{ [x]p:S({};`Y;x);({};x;p)}                             )
    (`"B*"      ;{ [x;y;z;w]({};x;({};y;({};z;w)))}                      )
    (`"C'"      ;{ [x;y;z;w]({};({};x;({};y;w));z)}                      )
    (`"S'"      ;{ [x;y;z;w]p:S w;({};({};x;({};y;p));({};z;p))}         ))

X[0]:(*X;_hash*X)

/ combinator valence

X_:{1++/";"=(x?"]")#x}'$X 1