Appearance
The .p.aif format
What aowlparser emits — enough to read a parse-dialect AIF by eye. This is the untyped wire form the nimony frontend consumes; the semantic pass later turns it into the typed .s.aif.
Shape
A .p.aif is a whitespace-insignificant tree of parenthesised nodes. Three token kinds appear:
- Trees —
(tag …children…). The tag is the first atom after(, glued to its line-info suffix. - Atoms — identifiers, integers, floats, strings (
"…"), chars. Plain atoms carry no tag; only typed/decorated literals do (seesuf). - Empties — a bare
.is an absent optional slot.
Inter-token whitespace is meaningless; aowlparser's indentation is pretty-print, not structure.
Header
Every file opens with three directives, one per line:
(.aif27)
(.vendor "aowlparser")
(.dialect "nim-parsed")(.aif27)— wire-format version 27.(.vendor "aowlparser")— producer id. aowlparser stamps its own name rather than nifler's"Nifler"; this line is the only deliberate byte difference from nifler output. See Differential testing.(.dialect "nim-parsed")— untyped, parser-level dialect.
The header is followed by the root (stmts …) tree carrying an absolute line-info of column 0, line 1, and the source filename.
Line-info suffixes
Every node can carry a position, encoded as a suffix glued directly onto the preceding tag or atom with no whitespace. An all-zero suffix is omitted.
| Form | Introducer | Meaning |
|---|---|---|
| Absolute | @ | the node's own (col, line[, file]) — root only |
| Relative | @ or ~ | delta from the parent's (col, line) — everywhere else |
Suffix grammar (each segment optional):
- Column —
@then the column; a negative column uses bare~(no@). Column0emits@with nothing after it. - Line —
,then the line delta; negative is~-then-digits; an interior zero collapses to just the comma. - File —
,then the filename (control chars escaped). Absolute root only.
Numbers are base62 (0-9A-Za-z = 0–61, most-significant first: A=10, G=16, J=19). Columns 0-based, lines 1-based. Relative deltas are measured against the parent baseline threaded down the descent (nifler's parent-relative scheme).
Example
assign.nim containing n = 3*n + 1:
(stmts@,1,assign.nim root, absolute: @ = col 0, ,1 = line 1, file "assign.nim"
(asgn@2 n~2 asgn at col +2 (the '='); target n at col −2
(infix@6 \2B infix at col +6; operator '+' escaped as \2B
(infix~3 * 3~1 n@1) inner infix at col −3; '*' raw; int 3 at −1; n at +1
1@2))) literal 1 at col +2(call@3 foo~3 1@1 2@4) is foo(1, 2). (proc@,2 fib@5 …) is a proc placed two lines below its parent. A zero-delta node ((cmd echo …)) carries no suffix.
Operator & atom escaping
An atom whose leading byte is ., a digit, +, -, ~, or a control character is escaped so it can't be read as a suffix or number: the leading byte becomes \HH. So + → \2B, - → \2D, .. → \2E\2E. Non-colliding operators (*, /, <, >, =) emit raw.
Tag vocabulary
The tags aowlparser emits, by category. (Plain identifiers, ints, floats, strings, chars, and . empties are atoms, not tags.)
Blocks & root : stmts (root and every block body), block, defer, staticstmt
Control flow : if, when, elif, else, while, for, case, of, ranges, try, except, fin
Flow keywords : ret, discard, raise, yld, break, continue, import, include, export, fromimport, comment
Declarations : asgn, var, let, const, type, proc, func, method, converter, iterator, macro, template, params, param, typevars, typevar, pragmas, pragmax, unpackdecl, unpacktup, unpackflat
Type expressions : object, enum, efld, fld, concept, tuple, proctype, itertype, and prefix modifiers ref, ptr, out, distinct, mut (nimony's spelling for var T)
Expressions : call, cmd, infix, prefix, dot, at, curlyat, bracket, par, tup, kv, vv, cast, expr, nil, quoted
Decorated literals : suf (typed numeric/string literal, e.g. 123u, 1.0'f32), callstrlit (ident"…")
For where each tag is emitted and the range-splitter that produces infix/prefix nesting, see Architecture and Grammar coverage.