SKICombinators UT¶

computation.spad line 1631 [edit on github]

UT: VarCat

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: from CoercibleTo 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

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

CoercibleTo OutputForm