47 lines
1.0 KiB
Plaintext
47 lines
1.0 KiB
Plaintext
Language "IBAFlang"
|
|
|
|
Syntax START:start ::= exp
|
|
|
|
Semantics start[[ _:start ]] : =>values
|
|
|
|
Rule start[[ E ]] =
|
|
initialise-binding finalise-failing eval[[ E ]]
|
|
|
|
Syntax E:exp ::= int
|
|
| id
|
|
| 'lambda' id '.' exp
|
|
| exp '(' exp ')'
|
|
| 'let' id '=' exp 'in' exp
|
|
| '(' exp ')'
|
|
|
|
Semantics eval[[ _:exp ]] : => values
|
|
|
|
Rule eval[[ N ]] = int[[ N ]]
|
|
|
|
Rule eval[[ X ]] = bound id[[ X ]]
|
|
|
|
Rule eval[[ 'lambda' X '.' E ]] =
|
|
function closure
|
|
scope( bind( id[[ X ]], given ),
|
|
eval[[ E ]] )
|
|
|
|
Rule eval[[ E1 '(' E2 ')' ]] =
|
|
apply( eval[[ E1 ]], eval[[ E2 ]] )
|
|
|
|
Rule eval[[ 'let' X '=' E1 'in' E2 ]] =
|
|
scope( bind( id[[ X ]], eval[[ E1 ]] ),
|
|
eval[[ E2 ]] )
|
|
|
|
Rule eval[[ '(' E ')' ]] = eval[[ E ]]
|
|
|
|
|
|
Lexis N:int ::= ('0'-'9')+
|
|
|
|
Semantics int[[ N:int ]] : => integers
|
|
= decimal \"N\"
|
|
|
|
|
|
Lexis X:id ::= ('a'-'z') ('a'-'z'|'0'-'9')*
|
|
|
|
Semantics id[[ X:id ]] : => identifiers
|
|
= \"X\" |