## Logiweb aspects of eval-at ( " , " , " ) in pyk

### The "pyk" aspect

Define pyk of eval-at ( asterisk , asterisk , asterisk ) as "eval-at ( "! , "! , "! )" end define

### The "value" aspect

define value of eval-at ( x , v , c ) as norm { x is val : { v is val : { c is val : if .not. { x r= quote x at y end quote } then LET seqeval ( x , c ) BE { asterisk IN LET { if asterisk atom then asterisk else { asterisk head } } :: { { if asterisk atom then asterisk else { asterisk tail } } :: true } BE { asterisk prime IN LET asterisk prime head BE { asterisk IN LET asterisk prime tail BE { asterisk prime IN LET asterisk BE { P IN LET asterisk prime head BE { asterisk IN LET asterisk prime tail BE { asterisk prime IN LET { if asterisk atom then asterisk else { asterisk head } } :: { { if asterisk atom then asterisk else { asterisk tail } } :: true } BE { asterisk prime prime IN LET asterisk prime prime head BE { asterisk IN LET asterisk prime prime tail BE { asterisk prime prime IN LET asterisk BE { C IN LET asterisk prime prime head BE { asterisk IN LET asterisk prime prime tail BE { asterisk prime prime IN LET { if asterisk atom then asterisk else { asterisk head } } :: { { if asterisk atom then asterisk else { asterisk tail } } :: true } BE { asterisk prime prime prime IN LET asterisk prime prime prime head BE { asterisk IN LET asterisk prime prime prime tail BE { asterisk prime prime prime IN LET asterisk BE { R IN LET asterisk prime prime prime head BE { asterisk IN LET asterisk prime prime prime tail BE { asterisk prime prime prime IN { P :: { C :: { eval-at1 ( R , v , true , x , c ) :: <<>> } } } } } } } } } } } } } } } } } } } } } } else if x second metaterm ( c ) then eval-at ( x first , x second :: v , c ) else error ( x , LocateProofLine ( x , c ) diag ( "At-seqop used on non-meta-term:" ) disp ( x second ) end diagnose ) } } } end define

The pyk compiler, version 0.1.9 by Klaus Grue,
GRD-2007-07-12.UTC:20:11:58.175987 = MJD-54293.TAI:20:12:31.175987 = LGT-4690987951175987e-6