WAST, the text format of WebAssembly, is a very low-level but human-readable and writable stack-based language. It is a tree of s-expressions, generally, though instructions can also be written linearly.
This is a Sublime Syntax definition for WAST. It requires Sublime Text version 3 or greater.
Using the themes Monokai, Propeller, Welded, and Excelsior (from ES Sublime) respectively:
I haven’t included any customized themes presently. I may add one later that highlights s-expressions by depth, since I think it would be an interesting experiment.
Functions, globals and types will appear in the local symbol list if they have been given names, but not if they’re anonymous (that is, only referenced by index).
Exports will appear in both the local and global symbol lists.
There is a definition for comments but, presently, no definition for indents. I still don’t know quite what that should look like — there seem to be some very different approaches to formatting s-expressions in the wild and I don’t have enough context yet to know which to choose. (Feedback or PRs welcome.)
The following scopes are provided. Mostly this sticks to TextMate conventions
but with additional precision in some cases and, for certain stuff, minor abuse
of not-quite-applicable-but-common scopes in order to help improve compatibility
with existing color schemes. In particular, I used storage.type.constant in
order to force distinct coloring for some things that are semantically not all
“constant”.
comment.block.wastcomment.line.wastconstant.character.escape.byte.wastconstant.character.escape.char.wastconstant.numeric.float.wastconstant.numeric.integer.wastentity.name.export.wastentity.name.function.wastentity.name.memory.wastentity.name.module.import.wastentity.name.module.wastentity.name.statement.wastentity.name.table.wastentity.name.type.wastinvalid.illegal.wastkeyword.control.conditional.wastkeyword.control.flow.wastkeyword.declaration.offset.wastkeyword.operator.assignment.wastkeyword.operator.word.wastkeyword.other.export.wastkeyword.other.import.wastkeyword.other.module.wastkeyword.other.offset.wastkeyword.other.start.wastmeta.block.conditional.wastmeta.block.loop.wastmeta.block.wastmeta.function-call.wastmeta.group.limit.wastmeta.invocation.wastmeta.s-expression.data.wastmeta.s-expression.elem.wastmeta.s-expression.export-description.wastmeta.s-expression.export.wastmeta.s-expression.expression.wastmeta.s-expression.function.wastmeta.s-expression.functype.wastmeta.s-expression.global.wastmeta.s-expression.globaltype.wastmeta.s-expression.import.wastmeta.s-expression.instruction.wastmeta.s-expression.local.wastmeta.s-expression.memory.wastmeta.s-expression.module.wastmeta.s-expression.offset.wastmeta.s-expression.param.wastmeta.s-expression.result.wastmeta.s-expression.start.begin.wastmeta.s-expression.table.wastmeta.s-expression.type.wastmeta.s-expression.typeuse.wastpunctuation.definition.block.begin.wastpunctuation.definition.block.conditional.begin.wastpunctuation.definition.block.conditional.end.wastpunctuation.definition.block.end.wastpunctuation.definition.block.loop.begin.wastpunctuation.definition.block.loop.end.wastpunctuation.definition.comment.begin.wastpunctuation.definition.comment.end.wastpunctuation.definition.data.begin.wastpunctuation.definition.data.end.wastpunctuation.definition.elem.begin.wastpunctuation.definition.elem.end.wastpunctuation.definition.export.begin.wastpunctuation.definition.export.end.wastpunctuation.definition.exportdesc.begin.wastpunctuation.definition.exportdesc.end.wastpunctuation.definition.expression.begin.wastpunctuation.definition.expression.end.wastpunctuation.definition.function.begin.wastpunctuation.definition.function.end.wastpunctuation.definition.functype.begin.wastpunctuation.definition.functype.end.wastpunctuation.definition.global.begin.wastpunctuation.definition.global.end.wastpunctuation.definition.globaltype.begin.wastpunctuation.definition.globaltype.end.wastpunctuation.definition.import.begin.wastpunctuation.definition.import.end.wastpunctuation.definition.instruction.begin.wastpunctuation.definition.instruction.end.wastpunctuation.definition.local.begin.wastpunctuation.definition.local.end.wastpunctuation.definition.memory.begin.wastpunctuation.definition.memory.end.wastpunctuation.definition.module.begin.wastpunctuation.definition.module.end.wastpunctuation.definition.offset.begin.wastpunctuation.definition.offset.end.wastpunctuation.definition.param.begin.wastpunctuation.definition.param.end.wastpunctuation.definition.result.begin.wastpunctuation.definition.result.end.wastpunctuation.definition.start.begin.wastpunctuation.definition.start.end.wastpunctuation.definition.string.begin.wastpunctuation.definition.string.end.wastpunctuation.definition.table.begin.wastpunctuation.definition.table.end.wastpunctuation.definition.type.begin.wastpunctuation.definition.type.end.wastpunctuation.definition.typeuse.begin.wastpunctuation.definition.typeuse.end.wastsource.waststorage.modifier.mutable.waststorage.modifier.result.waststorage.modifier.type.waststorage.modifier.waststorage.type.constant.waststorage.type.data.waststorage.type.elem.waststorage.type.function.waststorage.type.global.waststorage.type.local.waststorage.type.memory.waststorage.type.param.waststorage.type.table.waststorage.type.type.waststring.quoted.double.wastsupport.function.memory.wastsupport.function.numeric.wastsupport.function.variable.wastsupport.type.wastvariable.other.index.wastvariable.other.readwrite.wastvariable.other.wastvariable.parameter.wast
As with most languages, Sublime Syntax and Text Mate syntax definitions can model WAST correctly at the lexical level, but newline blindness prevents ideal scoping of some constructs.
In this case, however, there are not many issues that arise from this — really there’s just one. Whenever "(" is followed by a keyword, if there is a newline or a multiline comment between them, this syntax definition will not match that s-expression correctly. Since it would be unusual/unreadable if there really were newlines or comments in that position, I haven’t included any special recovery logic, only this caveat emptor.
Some higher level syntactic constraints are applied, like only allowing one start field, but plenty of other well-formedness constraints are not applied, even where they technically could be expressed in terms of Sublime Syntax.