From fca88d6e38968ec300100b0d919ae49df5d810a0 Mon Sep 17 00:00:00 2001 From: Marshall Lochbaum Date: Tue, 30 Nov 2021 22:18:41 -0500 Subject: Update block grammar --- docs/spec/grammar.html | 59 +++++++++++++++++++++++++------------------------- 1 file changed, 30 insertions(+), 29 deletions(-) (limited to 'docs/spec/grammar.html') diff --git a/docs/spec/grammar.html b/docs/spec/grammar.html index 8c002fb6..66814649 100644 --- a/docs/spec/grammar.html +++ b/docs/spec/grammar.html @@ -61,39 +61,40 @@ | lhs ASGN subExpr | lhs Derv "↩" subExpr? # Modified assignment -

A header looks like a name for the thing being headed, or its application to inputs (possibly twice in the case of modifiers). As with assignment, it is restricted to a simple form with no extra parentheses. The full list syntax is allowed for arguments. As a special rule, a monadic function header specifically can omit the function when the argument is not just a name (as this would conflict with a subject label). The following cases define only headers with arguments, which are assumed to be special cases; there can be any number of these. Headers without arguments can only refer to the general caseβ€”note that operands are not pattern matchedβ€”so there can be at most two of these kinds of headers, indicating the monadic and dyadic cases.

+

A header looks like a name for the thing being headed, or its application to inputs (possibly twice in the case of modifiers). As with assignment, it is restricted to a simple form with no extra parentheses. The full list syntax is allowed for arguments. A plain name is called a label and can be used for a block with or without arguments. First we define headers IMM_HEAD that include no arguments.

headW    = subject | "𝕨"
 headX    = subject | "𝕩"
 HeadF    = F | "𝕗" | "𝔽"
 HeadG    = F | "π•˜" | "𝔾"
-Mod1H1   = HeadF ( _m  | "_𝕣"  )
-Mod2H1   = HeadF ( _c_ | "_𝕣_" ) HeadG
-FuncHead = headW? ( F | "π•Š" ) headX
-         | sl | "(" subExpr ")" | brSub | list   # subject,
-         | ANY ( "β€Ώ" ANY )+                      # but not s
-         | UndoHead
-_m1Head  = headW? Mod1H1 headX
-_m2Head_ = headW? Mod2H1 headX
-
-

Additionally, an inference header doesn't affect evaluation of the function, but describes how an inferred property (Undo) should be computed. Here "˜" and "⁼" are both specific instances of the _ml token.

-
UndoHead = headW? ( F | "π•Š" )      "⁼" headX
-         | headW  ( F | "π•Š" ) "˜"  "⁼" headX
-         |        ( F | "π•Š" ) "˜"? "⁼"
+FuncLab  = F | "π•Š"
+Mod1Lab  = _m  | "_𝕣"
+Mod2Lab  = _c_ | "_𝕣_"
+FuncName = FuncLab
+Mod1Name = HeadF Mod1Lab
+Mod2Name = HeadF Mod2Lab HeadG
+LABEL    =         FuncLab  | Mod1Lab  | Mod2Lab
+IMM_HEAD = LABEL | FuncName | Mod1Name | Mod2Name
-

A braced block contains bodies, which are lists of statements, separated by semicolons and possibly preceded by headers, which are separated from the body with a colon. A non-final expression can be made into a predicate by following it with the separator-like ?. Multiple bodies allow different handling for various cases, which are pattern-matched by headers. For an immediate block there are no inputs, so there can only be one possible case and one body. Functions and modifiers allow any number of "matched" bodies, with headers that have arguments, followed by at most two "main" bodies with either no headers or headers without arguments. If there is one main body, it is ambivalent, but two main bodies refer to the monadic and dyadic cases.

+

There are some extra possibilities for a header that specifies arguments. As a special rule, a monadic function header specifically can omit the function when the argument is not just a name (as this would conflict with a subject label). Additionally, an inference header doesn't affect evaluation of the function, but describes how an inferred property (Undo) should be computed. Here "˜" and "⁼" are both specific instances of the _ml token.

+
ARG_HEAD = LABEL
+         | headW? IMM_HEAD      "⁼"? headX
+         | headW  IMM_HEAD "˜"  "⁼"  headX
+         |        FuncName "˜"? "⁼"
+         | CaseHead
+CaseHead = sl | "(" subExpr ")" | brSub | list   # subject,
+         | ANY ( "β€Ώ" ANY )+                      # but not s
+
+

A braced block contains bodies, which are lists of statements, separated by semicolons and possibly preceded by headers, which are separated from the body with a colon. A non-final expression can be made into a predicate by following it with the separator-like ?. Multiple bodies allow different handling for various cases, which are pattern-matched by headers. A block can have any number of bodies with headers. After these there can be bodies without headersβ€”up to one for an immediate block and up to two for a block with arguments. If a block with arguments has one such body, it's ambivalent, but two of them refer to the monadic and dyadic cases.

BODY     = β‹„? ( STMT β‹„ | EXPR β‹„? "?" β‹„? )* STMT β‹„?
-FCase    = β‹„? FuncHead ":" BODY
-_mCase   = β‹„? _m1Head  ":" BODY
-_cCase_  = β‹„? _m2Head_ ":" BODY
-FMain    = ( β‹„? (  F  |  "π•Š"           ) ":" )? BODY
-_mMain   = ( β‹„? ( _m  | "_𝕣"  | Mod1H1 ) ":" )? BODY
-_cMain_  = ( β‹„? ( _c_ | "_𝕣_" | Mod2H1 ) ":" )? BODY
+IMM_BLK  = "{" ( β‹„? IMM_HEAD β‹„? ":" BODY ";" )* BODY? "}"
+ARG_BLK  = "{" ( β‹„? ARG_HEAD β‹„? ":" BODY ";" )* ( BODY ( ";" BODY )? )? "}"
+BLOCK    = IMM_BLOCK | ARG_BLOCK
 brSub    = "{" ( β‹„? s ":" )? BODY "}"
-BrFunc   = "{" (  FCase  ";" )* (  FCase  |  FMain ( ";"  FMain )? ) "}"
-_brMod1  = "{" ( _mCase  ";" )* ( _mCase  | _mMain ( ";" _mMain )? ) "}"
-_brMod2_ = "{" ( _cCase_ ";" )* ( _cCase_ | _cMan_ ( ";" _cMan_ )? ) "}"
+BrFunc   = BLOCK
+_brMod1  = BLOCK
+_brMod2_ = BLOCK
-

Two additional rules apply to blocks, based on the special name associations in the table below. First, each block allows the special names in its column to be used as the given token types within BODY terms (not headers). Except for the spaces labelled "None", each column is cumulative and a given entry also includes all the entries above it. Second, for BrFunc, _brMod1, and _brMod2_ terms, if no header is given, then at least one BODY term in it must contain one of the names on, and not above, the corresponding row. Otherwise the syntax would be ambiguous, since for example a simple "{" BODY "}" sequence could have any type.

+

Three additional rules apply to blocks, allowing the ambiguous grammar above to be disambiguated. They are shown in the table below. First, each block type allows the special names in its row to be used as the given token types within BODY terms (not headers). Except for the spaces labelled "None", each of these four columns is cumulative, so that a given entry also includes all the entries above it. Second, a block can't contain one of the tokens from the "label" column of a different row. Third, each BrFunc, _brMod1, and _brMod2_ term must contain one of the names on, and not above, the corresponding row (including the "label" column).

@@ -102,7 +103,7 @@ - + @@ -120,7 +121,7 @@ - + @@ -128,7 +129,7 @@ - + @@ -136,7 +137,7 @@ - +
F _m _c_otherlabel
π•Žπ•π•Š ";"FuncLab
_brMod1𝔽 _𝕣 Mod1Lab
_brMod2_𝔾 None _𝕣_Mod2Lab
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