Wolfram Language Paclet Repository
Community-contributed installable additions to the Wolfram Language
Wolfram`Parser`
ParseChainLeft  |
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▪
op returns its combining function. op matches an operator token and yields a binary function, applied as — the same op-returns-a-function convention as . Attach it with : .
f[left,right]
ParseAction[ParseLiteral["-"],(Subtract&)]
▪
Left-associative fold. Operands accumulate left to right: becomes . For this makes evaluate as .
poppopp
f[f[f[p1,p2],p3],p4]
1-2-3
(1-2)-3
▪
One or more operands. At least one p is required, so empty input fails. A lone operand with no following operator returns that operand itself, not a one-element list.
▪
Mixed operators share the level. When op is a of several operator parsers, each returning its own function, they associate together left to right — for example and in one additive chain.
+
-
▪
One precedence level. handles a single operator precedence. For several levels, or for prefix / postfix operators, use — its one--operator table is exactly this combinator, in one linear pass.
ParseChainLeft
"InfixL"
▪
Result type: whatever op's function returns, not necessarily a list.
Examples
(13)
Basic Examples
(3)
Left-associative subtraction — the chain folds as :
1-2-3
(1-2)-3
In[1]:=
num=
[DigitCharacter],FromDigits;sub=
["-"],(Subtract&);
[num,sub],"1-2-3"
 | ParseAction |
 | ParseCharacter |
| ParseAction |
| ParseLiteral |
 | Parse |
| ParseChainLeft |
Out[1]=
-4
A single operand, with no operator, returns the operand itself — not and not :
{5}
f[5]
In[1]:=
| Parse |
| ParseChainLeft |
Out[1]=
5
In[1]:=
plus=
["+"],(Plus&);
[num,plus],"1+2+3+4"
| ParseAction |
| ParseLiteral |
| Parse |
| ParseChainLeft |
Out[1]=
10
Scope
(4)
Properties & Relations
(3)
Possible Issues
(2)
Neat Examples
(1)
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