Wolfram Language Paclet Repository
Community-contributed installable additions to the Wolfram Language
Wolfram`Parser`Languages`Lambda`
LambdaEval  |
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LambdaEval
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The surface syntax is namebody (or the unicode namebody) for abstraction, juxtaposition for application (left associative), and parentheses for grouping. is sugar for . In a Wolfram string a backslash doubles, so the term is written .
\
.
λ
.
\xy.b
\x.\y.b
\x.x
"\\x.x"
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Each bound variable is renamed to a fresh symbol when its abstraction compiles, so shadowing is capture-safe: an inner binder replaces its own occurrences before an outer one runs.
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A free variable folds to the matching Wolfram , so a term with unbound names returns a symbolic expression rather than a closure.
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To see the standard syntax tree for the same input instead, use , which runs the same grammar over the abstract-syntax algebra.
Examples
(4)
Basic Examples
(1)
The K combinator projects its first argument - the kernel reduces both applications:
(\x.\y.x)ab
In[1]:=
 | LambdaEval |
Out[1]=
a
Its dual projects the second argument:
\x.\y.y
In[2]:=
| LambdaEval |
Out[2]=
b
In[3]:=
| LambdaAST |
Out[3]=
ContainerNode[String,{CallNode[CallNode[CallNode[LeafNode[Symbol,λ,],{LeafNode[Symbol,x,],CallNode[LeafNode[Symbol,λ,],{LeafNode[Symbol,y,],LeafNode[Symbol,x,Source{{1,8},{1,9}}]},Source{{1,8},{1,9}}]},Source{{1,8},{1,9}}],{LeafNode[Symbol,a,Source{{1,11},{1,12}}]},Source{{1,8},{1,12}}],{LeafNode[Symbol,b,Source{{1,13},{1,14}}]},Source{{1,8},{1,14}}]},Source{{1,8},{1,14}}]
Scope
(1)
Properties & Relations
(1)
Possible Issues
(1)
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