# SKICombinators UT¶

parse result includes term returned and new index

=: (%, %) -> Boolean

return true if equal (deep search) that is: all terms at all levels in tree must be equal to return true all terms must be exactly equal, not just equivalent, that is SKK=I will return false even though ‘SKK’ and ‘I’ have the same effect

~=: (%, %) -> Boolean

from BasicType

atom?: % -> Boolean

returns true if this is an atom, that is a leaf node otherwise return false if this is a compound term

coerce: % -> OutputForm
freeVariable?: (%, UT) -> Boolean

the variable indicated by 's' is free if it does not appear in node 'n' or any of its subnodes.

getChildren: % -> List %

returns child nodes if this is a compound term otherwise returns []

getVariable: % -> UT

returns the variable, if this is not a variable then return I

hash: % -> SingleInteger

from SetCategory

hashUpdate!: (HashState, %) -> HashState

from SetCategory

I: () -> %

Constructs a I combinator

isI?: % -> Boolean

returns true if this is an I combinator node

isK?: % -> Boolean

returns true if this is a K combinator node

isS?: % -> Boolean

returns true if this is a S combinator node

K: () -> %

Constructs a K combinator

latex: % -> String

from SetCategory

parseSki: String -> %

Constructs combinators from a string

parseTerm: (String, NonNegativeInteger) -> Record(rft: %, pout: NonNegativeInteger)

parseTerm is used by parseSki. It would rarely be called externally but it is here to allow it to call parseSki that is to allow circular calls

redux: % -> %

weak reduction - apply this combinator to rearrange its subnodes then apply recursively to its subnodes.

S: () -> %

Constructs a S combinator

ski: (%, %) -> %

Constructs a node combinator over combinators

ski: UT -> %

Constructs variable combinator

toString: % -> String

output

variable?: % -> Boolean

returns true if this is an variable

BasicType

SetCategory